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/link2.frag

@@ -18,3 +18,16 @@ ivec2 foo()
 }
 
 vec4 f = e * e;
+
+const vec3 cv3 = vec3(43.0, 0.34, 9.9);
+const vec3 cv3e = vec3(43.0, 0.34, 2.9);
+uniform mat2 um2 = mat2(4.0);
+uniform mat2 um2n;
+uniform mat2 um2e = mat2(3.0);
+struct S {
+    int a;
+    float b;
+};
+uniform S s = S(82, 3.9);
+uniform S sn = S(82, 3.9);
+uniform S se = S(81, 3.9);