glslang PP: make decimal number parser clearer and add boundary tests.  Also, disable the warning for "do {} while (true);"


git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@31215 e7fa87d3-cd2b-0410-9028-fcbf551c1848