add BUILD_NATIVE_BENCHMARK

Similar to BUILD_NATIVE_TEST, but links against libbenchmark
instead of libgtest.

Change-Id: I97d44db4807a79efa9bca56c108082ac45c943b8
Back to odexed
Allow clang to build host binaries.

Change-Id: I7e4f9dc6f69a97cfefdfa2ed55c5d7b8ad496da7

Conflicts:
	core/binary.mk
	core/executable.mk
	core/llvm_config.mk
	core/shared_library.mk