Bring the Bazel build in sync with the CMake build.

1. Remove defines which are not used anymore.
2. Enable CXX11 threading.
3. Enable EIGEN_SPARSE by default.

Change-Id: I841ba517367e6b204475e5255c91313f01a5bcdb

bazel/ceres.bzl

diff --git a/bazel/ceres.bzl b/bazel/ceres.bzl
index 8963370..ea6392a 100644
--- a/bazel/ceres.bzl
+++ b/bazel/ceres.bzl
@@ -193,9 +193,9 @@
         defines = [
             "CERES_NO_SUITESPARSE",
             "CERES_NO_CXSPARSE",
-            "CERES_NO_THREADS",
             "CERES_NO_LAPACK",
-            "CERES_STD_UNORDERED_MAP",
+            "CERES_USE_EIGEN_SPARSE",
+            "CERES_USE_CXX11_THREADS",
             "CERES_GFLAGS_NAMESPACE=" + gflags_namespace,
         ],
         includes = [