openblas.cmake: Added an additional step for installing links. Previously, the links pointed to a non-existent libopenblas.so on Mac. Now, links on Mac point to libopenblas.dylib.
spams-python.cmake: Updated to pass environment variable namely BUILDEM_DIR, GCC, and GXX. The variables GCC and GXX should point to GNU gcc and g++ compilers, respectively.
patches/spams-python-setup.patch: Simplified the patch to avoid issues on Mac with specifying which libraries to build statically and which to build dynamically.