Relax mediump interpolation accuracy requirements and clarify thresholds
This change relaxes mediump interpolation accuracy in
dEQP-GLES3.functional.fragment_out.* to 4 ULP from 1 ULP.
Threshold computation is also fixed/clarified by moving interpolation
threshold to be dependent on precision qualifier, and allowing only
rounding difference in format-dependent threshold. The original error
was likely due to incorrectly accomodating for interpolation in format
1 file changed