Add grammar productions for adding 'invariant' to already declared variables.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@22083 e7fa87d3-cd2b-0410-9028-fcbf551c1848

Test/120.vert

@@ -8,8 +8,9 @@ attribute vec4 attv4;
 uniform sampler2D s2D;
 invariant varying vec2 centTexCoord;
 invariant gl_Position;
-
+centroid gl_Position;
 centroid centroid foo;
+invariant gl_Position, gl_PointSize;
 
 void main()
 {
@@ -22,6 +23,8 @@ void main()
 
     float f[];
     int a = f.length();
+
+    gl_PointSize = 3.8;
 }
 
 uniform float initted = 3.4;

Test/specExamples.vert

@@ -97,8 +97,8 @@ layout (binding=3) uniform atomic_uint c2;           // offset = 8
 layout (binding=2) uniform atomic_uint d2;           // offset = 4
 
 //layout (offset=4)                // error, must include binding
-layout (binding=1, offset=0)  a; // okay
-layout (binding=2, offset=0)  b; // okay
+//layout (binding=1, offset=0)  a; // okay
+//layout (binding=2, offset=0)  b; // okay
 //layout (binding=1, offset=0)  c; // error, offsets must not be shared
 //                                 //        between a and c
 //layout (binding=1, offset=2)  d; // error, overlaps offset 0 of a