Add Android NDK build files.

This adds a Android.mk build that builds a Ceres static library
suitable for embetting in larger Android applications. This is
useful when needing to build Ceres without GPL'd components, since
the standalone toolchain (needed for the CMake Android build) does
not work with STLPort.

Change-Id: I8d857237f6f82658741017d161b2e31d9a20e5a7
diff --git a/jni/Android.mk b/jni/Android.mk
new file mode 100644
index 0000000..ef31946
--- /dev/null
+++ b/jni/Android.mk
@@ -0,0 +1,176 @@
+# Ceres Solver - A fast non-linear least squares minimizer
+# Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
+# http://code.google.com/p/ceres-solver/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# * Redistributions of source code must retain the above copyright notice,
+#   this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+# * Neither the name of Google Inc. nor the names of its contributors may be
+#   used to endorse or promote products derived from this software without
+#   specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+# Author: settinger@google.com (Scott Ettinger)
+#         keir@google.com (Keir Mierle)
+#
+# Builds Ceres for Android, using the standard toolchain (not standalone). It
+# uses STLPort instead of GNU C++. This is useful for anyone wishing to ship
+# GPL-free code. This cannot build the tests or other parts of Ceres; only the
+# core libraries. If you need a more complete Ceres build, consider using the
+# CMake toolchain (noting that the standalone toolchain doesn't work with
+# STLPort).
+#
+# You will have to specify the environment EIGEN_PATH to point to the Eigen
+# sources when building. For example:
+#
+#   EIGEN_PATH=/home/keir/src/eigen-3.0.5 ndk-build -j
+#
+# It is also possible to specify CERES_EXTRA_DEFINES, in case you need to pass
+# more definitions to the C compiler.
+#
+# IMPORTANT:
+#
+# The shared library built at the bottom is fake, broken, and empty. It exists
+# only to force ndk-build to build the shared library. This shouldn't be
+# necessary, but if it is missing, then ndk-build will do nothing when asked to
+# build. The produced .so library is NON-FUNCTIONAL since it has no Ceres
+# function-level dependencies. Instead, copy the static library:
+#
+#   ../obj/local/armeabi-v7a/libceres.a
+#
+# into your own project, then link it into your binary in your Android.mk file.
+#
+# Reducing binary size:
+#
+# This build includes the Schur specializations, which cause binary bloat. If
+# you don't need them for your application, consider adding:
+#
+#   -DCERES_RESTRICT_SCHUR_SPECIALIZATION
+#
+# to the LOCAL_CFLAGS variable below, and commenting out all the
+# generated/schur_eliminator_2_2_2.cc-alike files, leaving only the _d_d_d one.
+
+LOCAL_PATH := $(call my-dir)
+
+EIGEN_PATH := $(EIGEN_PATH)
+
+CERES_INCLUDE_PATHS := ../internal
+CERES_INCLUDE_PATHS += ../internal/ceres
+CERES_INCLUDE_PATHS += ../include
+CERES_INCLUDE_PATHS += ../internal/ceres/miniglog
+CERES_SRC_PATH := ../internal/ceres
+
+include $(CLEAR_VARS)
+LOCAL_C_INCLUDES := $(CERES_INCLUDE_PATHS)
+LOCAL_C_INCLUDES += $(EIGEN_PATH)
+
+LOCAL_CPP_EXTENSION := .cc
+LOCAL_CPPFLAGS += -O3
+LOCAL_CFLAGS := $(CERES_EXTRA_DEFINES) \
+                -DCERES_DONT_HAVE_PROTOCOL_BUFFERS \
+                -DCERES_NO_SUITESPARSE \
+                -DCERES_NO_GFLAGS \
+                -DCERES_NO_THREADS \
+                -DCERES_NO_CXSPARSE \
+                -DCERES_NO_TR1
+
+LOCAL_SRC_FILES := $(CERES_SRC_PATH)/array_utils.cc \
+                   $(CERES_SRC_PATH)/block_evaluate_preparer.cc \
+                   $(CERES_SRC_PATH)/block_jacobian_writer.cc \
+                   $(CERES_SRC_PATH)/block_jacobi_preconditioner.cc \
+                   $(CERES_SRC_PATH)/block_random_access_dense_matrix.cc \
+                   $(CERES_SRC_PATH)/block_random_access_matrix.cc \
+                   $(CERES_SRC_PATH)/block_random_access_sparse_matrix.cc \
+                   $(CERES_SRC_PATH)/block_sparse_matrix.cc \
+                   $(CERES_SRC_PATH)/block_structure.cc \
+                   $(CERES_SRC_PATH)/canonical_views_clustering.cc \
+                   $(CERES_SRC_PATH)/cgnr_solver.cc \
+                   $(CERES_SRC_PATH)/compressed_row_jacobian_writer.cc \
+                   $(CERES_SRC_PATH)/compressed_row_sparse_matrix.cc \
+                   $(CERES_SRC_PATH)/conditioned_cost_function.cc \
+                   $(CERES_SRC_PATH)/conjugate_gradients_solver.cc \
+                   $(CERES_SRC_PATH)/corrector.cc \
+                   $(CERES_SRC_PATH)/dense_qr_solver.cc \
+                   $(CERES_SRC_PATH)/dense_sparse_matrix.cc \
+                   $(CERES_SRC_PATH)/detect_structure.cc \
+                   $(CERES_SRC_PATH)/dogleg_strategy.cc \
+                   $(CERES_SRC_PATH)/evaluator.cc \
+                   $(CERES_SRC_PATH)/file.cc \
+                   $(CERES_SRC_PATH)/gradient_checking_cost_function.cc \
+                   $(CERES_SRC_PATH)/implicit_schur_complement.cc \
+                   $(CERES_SRC_PATH)/iterative_schur_complement_solver.cc \
+                   $(CERES_SRC_PATH)/levenberg_marquardt_strategy.cc \
+                   $(CERES_SRC_PATH)/linear_least_squares_problems.cc \
+                   $(CERES_SRC_PATH)/linear_operator.cc \
+                   $(CERES_SRC_PATH)/linear_solver.cc \
+                   $(CERES_SRC_PATH)/local_parameterization.cc \
+                   $(CERES_SRC_PATH)/loss_function.cc \
+                   $(CERES_SRC_PATH)/normal_prior.cc \
+                   $(CERES_SRC_PATH)/partitioned_matrix_view.cc \
+                   $(CERES_SRC_PATH)/polynomial_solver.cc \
+                   $(CERES_SRC_PATH)/problem.cc \
+                   $(CERES_SRC_PATH)/problem_impl.cc \
+                   $(CERES_SRC_PATH)/program.cc \
+                   $(CERES_SRC_PATH)/residual_block.cc \
+                   $(CERES_SRC_PATH)/residual_block_utils.cc \
+                   $(CERES_SRC_PATH)/runtime_numeric_diff_cost_function.cc \
+                   $(CERES_SRC_PATH)/schur_complement_solver.cc \
+                   $(CERES_SRC_PATH)/schur_eliminator.cc \
+                   $(CERES_SRC_PATH)/schur_ordering.cc \
+                   $(CERES_SRC_PATH)/scratch_evaluate_preparer.cc \
+                   $(CERES_SRC_PATH)/solver.cc \
+                   $(CERES_SRC_PATH)/solver_impl.cc \
+                   $(CERES_SRC_PATH)/sparse_matrix.cc \
+                   $(CERES_SRC_PATH)/sparse_normal_cholesky_solver.cc \
+                   $(CERES_SRC_PATH)/split.cc \
+                   $(CERES_SRC_PATH)/stringprintf.cc \
+                   $(CERES_SRC_PATH)/suitesparse.cc \
+                   $(CERES_SRC_PATH)/triplet_sparse_matrix.cc \
+                   $(CERES_SRC_PATH)/trust_region_minimizer.cc \
+                   $(CERES_SRC_PATH)/trust_region_strategy.cc \
+                   $(CERES_SRC_PATH)/types.cc \
+                   $(CERES_SRC_PATH)/visibility_based_preconditioner.cc \
+                   $(CERES_SRC_PATH)/visibility.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_d_d_d.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_2_2.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_2_3.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_2_4.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_2_d.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_3_3.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_3_4.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_3_9.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_3_d.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_4_3.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_4_4.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_2_4_d.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_4_4_2.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_4_4_3.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_4_4_4.cc \
+                   $(CERES_SRC_PATH)/generated/schur_eliminator_4_4_d.cc
+
+LOCAL_MODULE := ceres
+include $(BUILD_STATIC_LIBRARY)
+
+# This is a fake library; see the file header comments.
+include $(CLEAR_VARS)
+LOCAL_C_INCLUDES := $(CERES_INCLUDE_PATHS)
+LOCAL_C_INCLUDES += $(EIGEN_PATH)
+LOCAL_MODULE := forces_static_ceres_build_do_not_use
+LOCAL_STATIC_LIBRARIES := ceres
+include $(BUILD_SHARED_LIBRARY)