reporting missing headers & C files.
this is important so IDE's using CMake integration always get blender headers. - QtCreator & MSVC for eg, probably others too.
by cmake devs.
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.