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/420.vert.out

@@ -22,7 +22,8 @@ ERROR: node is still EOpNull!
 0:18        Condition
 0:18        Compare Equal (bool)
 0:18          'i' (int)
-0:18          3 (const int)
+0:18          Constant:
+0:18            3 (const int)
 0:18        true case
 0:19        Sequence
 0:19          move second child to first child (int)
@@ -30,7 +31,8 @@ ERROR: node is still EOpNull!
 0:19            'i' (int)
 0:25      Loop with condition tested first
 0:25        Loop Condition
-0:25        true (const bool)
+0:25        Constant:
+0:25          true (const bool)
 0:25        No loop body
 0:30  Function Definition: bar(vf4; (void)
 0:30    Function Parameters: