Create linkage symbol nodes in the AST so a linker has access to all global objects that were declared, for error checking, etc. Use it now for all ins/outs/uniforms as well as gl_VertexID and gl_InstanceID.

Also fixed a confusing name and added more 'const'.


git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@22142 e7fa87d3-cd2b-0410-9028-fcbf551c1848

Test/300block.frag

@@ -34,6 +34,11 @@ uniform barBlockArray {
     int ni;
 } insts[4];
 
+uniform unreferenced {
+    float f;
+    uint u;
+};
+
 void main()
 {
     texture(s.sampler, vec3(inst.ni, bv.y, insts[2].nbv.z));