[glean-dev] scons -> cmake

[Jose F. <jfo...@vm...>]

I've made a new branch, "cmake", where I replace scons build system with cmake.

Although cmake is less powerfull, in respect with convenience library support -- not needed by glean --, it requires much less costumization/maintainance effort, and is easier to use. So, in similarity with mesa demos, I've decided to replace scons with cmake as a cross-platform build system.

I've tested this with linux, msvc, cross-mingw32, and mac os x.

Let me know if there are any concerns before I merge this branch into master.

Jose