Fix resizing of gl_PrimitiveIndicesNV[] to max_primitives*geomSize

- This change also allows redeclaration of gl_PrimitiveIndicesNV and
  adds error checks against incorrect explicit array size.
- Also modifies gtests to check array bound limits and redeclare gl_PrimitiveIndicesNV[].

Test/spv.meshShaderRedeclBuiltins.mesh

@@ -22,14 +22,16 @@ out gl_MeshPerVertexNV {
     float gl_PointSize;
     float gl_ClipDistance[4];
     float gl_CullDistance[4];
-} gl_MeshVerticesNV[];
+} gl_MeshVerticesNV[MAX_VER];       // explicitly sized to MAX_VER
 
 perprimitiveNV out gl_MeshPerPrimitiveNV {
     int gl_PrimitiveID;
     int gl_Layer;
     int gl_ViewportIndex;
     int gl_ViewportMask[];
-} gl_MeshPrimitivesNV[];
+} gl_MeshPrimitivesNV[];            // implicitly sized to MAX_PRIM
+
+out uint gl_PrimitiveIndicesNV[];   // explicitly sized to MAX_PRIM * 3
 
 void main()
 {
@@ -63,4 +65,9 @@ void main()
     gl_MeshPrimitivesNV[iid+1].gl_ViewportMask[0] = gl_MeshPrimitivesNV[iid].gl_ViewportMask[0];
 
     BARRIER();
+
+    // check bound limits
+    gl_PrimitiveIndicesNV[0] = 1;
+    gl_PrimitiveIndicesNV[(MAX_PRIM * 3) - 1] = 2;
+    gl_PrimitiveCountNV = MAX_PRIM * 3;
 }