Blender Git Loki

CMake: De-duplicate checks around unordered maps and shared pointer

Previously several areas were calling TEST_SHARED_PTR_SUPPORT and
TEST_UNORDERED_MAP_SUPPORT which isn't that bad on it's own but
was causing some quite verbose output with same information line
printed multiple times. additionally, what's more worse, define flags
for Ceres were duplicated in main CMakeLists and Ceres's CMakeLists.

Now we've got a single place where checks for those classes are
happening and other areas are simply checking for variables set by
those check macros, keeping CMake output clean and nice.