Multiple dense linear algebra backends.

1. When a LAPACK implementation is present, then
DENSE_QR, DENSE_NORMAL_CHOLESKY and DENSE_SCHUR
can use it for doing dense linear algebra operations.

2. The user can switch dense linear algebra libraries
by setting Solver::Options::dense_linear_algebra_library_type.

3. Solver::Options::sparse_linear_algebra_library is now
Solver::Options::sparse_linear_algebra_library_type to be consistent
with all the other enums in Solver::Options.

4. Updated documentation as well as Solver::Summary::FullReport
to reflect these changes.

Change-Id: I5ab930bc15e90906b648bc399b551e6bd5d6498f
diff --git a/jni/Android.mk b/jni/Android.mk
index b881d88..d628177 100644
--- a/jni/Android.mk
+++ b/jni/Android.mk
@@ -99,6 +99,7 @@
 
 LOCAL_CPP_EXTENSION := .cc
 LOCAL_CFLAGS := $(CERES_EXTRA_DEFINES) \
+                -DCERES_NO_LAPACK \
                 -DCERES_NO_SUITESPARSE \
                 -DCERES_NO_GFLAGS \
                 -DCERES_NO_THREADS \