blender_add_lib now takes a separate include argument to suppress warnings in system includes (mostly ffmpeg & python).
also only build wm_apple.c on apple+carbon configuration.
Simple python benchmark shows this to be about 3x faster in the case where an update isn't needed.
This also speeds up rna function argument parsing, since each arg in a function call did 2 string lookups on the context which were never needed.
globbing vs explicit is discussed here.
http://www.cmake.org/pipermail/cmake/2008-December/025694.html
Practical implications are:
- developers need to keep CMakeLists.txt files up to date.
- Users wont get strange linking errors if they build after a file is added, since CMake detects CMakeLists.txt is modified and automatically reconfigure.
