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.geom

@@ -15,3 +15,5 @@ void main()
     gl_in[3].gl_Position; // ERROR, out of range
     gl_CullDistance[2] = gl_in[1].gl_CullDistance[2];
 }
+
+layout(points) in float f[3];  // ERROR, must be standalone