Set target from host_os.
Introduce toolchain variable.
Build COMPILE and LINK macros.
M-x delete-trailing-whitespace
Fix: undefined reference to symbol 'XDestroyWindow'.
Fix: Inconsistency detected by ld.so: dl-version.c: 224:
_dl_check_map_versions: Assertion `needed != ((void *)0)' failed!

See details on: http://stackoverflow.com/questions/20007961/error-running-a-compiled-c-file-uses-opengl-error-inconsistency-detected
Available for customization bprefix - build dir prefix.
Merge