Add full support for uniforms with initializers, including intra-stage link validation of aggregate constant initializers.

This included 
 - encapsulating aggregate constants
 - removal of constant-aggregate comparison algorithms, instead using a flattened and direct std::vector comparison
 - adding structure type comparison for independently declared structures that still might match types



git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@23274 e7fa87d3-cd2b-0410-9028-fcbf551c1848

Test/baseResults/errors.frag.out

@@ -9,6 +9,7 @@ ERROR: node is still EOpNull!
 0:1      'foo' (in mediump int)
 0:3    Sequence
 0:3      Branch: Return with expression
-0:3        1 (const int)
+0:3        Constant:
+0:3          1 (const int)
 0:?   Linker Objects