CMake: Collapse into a single library all the libraries under the glslang directory, and represent the proper hierarchy in MSVS. There are still a total of 3 libraries to link against: glslang, OGLCompiler, and OSDependent.
git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@26137 e7fa87d3-cd2b-0410-9028-fcbf551c1848
