Apply patch to ax_cxx_compile_stdcxx_11 so that C++11 support is correctly identified on Mac OS 10.8.
Apply patch to ax_cxx_compile_stdcxx_11 so that C++11 support is
correctly identified on Mac OS 10.8.

schwa-lab/libschwa,schwa-lab/libschwa,schwa-lab/libschwa,schwa-lab/libschwa