GLSL: validation of early_fragment_tests, others, on an object.

Some layout qualifiers must not be on an object and had a TBD for testing
them: early_fragment_tests, cw/ccw, points, point_mode, and
fractional_even_spacing/fractional_odd_spacing/equal_spacing.

Test/450.frag

@@ -64,3 +64,5 @@ layout(location = 12) in bName2 {
     float f;
     layout(location = 13) float g;  // ERROR, location on array
 } bInst2[3];
+
+layout(early_fragment_tests) in float f; // ERROR, must be standalone