glsl: fix invariant qualifer usage and matching rule for GLSL 4.20
I noticed that GLSL version referenced here was wrong, version 4.20 is first spec that does not allow invariant keyword for inputs.
Fixes: f9f46293 ("glsl: Fix invariant matching in GLSL 4.30 and GLSL ES 1.00.") Signed-off-by: Tapani Pälli tapani.palli@intel.com