Update gtest to explicitly size gl_PrimitiveIndicesNV[]

Test/spv.meshShaderRedeclBuiltins.mesh

@@ -31,7 +31,7 @@ perprimitiveNV out gl_MeshPerPrimitiveNV {
     int gl_ViewportMask[];
 } gl_MeshPrimitivesNV[];                        // implicitly sized to MAX_PRIM
 
-out uint gl_PrimitiveIndicesNV[];   // explicitly sized to MAX_PRIM * 3
+out uint gl_PrimitiveIndicesNV[MAX_PRIM*3];     // explicitly sized to MAX_PRIM * 3
 
 void main()
 {