glslang is using C++ 11, which has first class support for variables of the `thread_local` storage class.
By dropping the use of the `OS_[GS]etTLSValue`, we can simplify the logic, and have it support a thread-local default allocator if none is provided.
Issue: #2346
- the new C++ style interface now stands on its own, with the addition of glslang::InitializeProcess() and glslang::FinalizeProcess()
- more "global" pool names from a decade ago are fixed to be thread names
- StandAlone.cpp fully uses one of the old-style interface or new C++ style interface
git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@23851 e7fa87d3-cd2b-0410-9028-fcbf551c1848