Connor Abbott authored Jan 18, 2022 and Marge Bot committed Jan 21, 2022

This appears to do the same thing as CLAMPENABLE on a3xx. That is, it
clamps the result to [0, 1] for unorm formats and [-1, 1] for snorm
formats *after* filtering. In particular it's now more easily observable
with cubic filtering, because cubic filtering can produce values outside
the original range. Presumably this only matters with linear filtering
due to rounding errors when computing the weighted average.

Part-of: <mesa/mesa!14613>