Built-in symbol tables now lazily evaluated, and driven by per version, per profile input.  Got all ES 100 and ES 300 built-in symbols correct.

This includes
 - doing prescan of shader to know version/profile before parsing it
 - putting precision qualifiers on built-in ES symbols
 - getting most built-in state correct for core/compatibility/missing profile
 - adding gl_VertexID and gl_InstanceID, among other ES 300 built-in symbols
 - adding the ES 300 gl_Max/Min constants
 - accepting shaders that contain nothing but whitespace without generating an error


git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@20627 e7fa87d3-cd2b-0410-9028-fcbf551c1848