[Mesa-dev] NIR function inlining for faster compile times

[Timothy Arceri]

This series is part of an effort to reduce the regression in compile
times when switching radeonsi from TGIS -> NIR. But it also turns
out to be quite handy for i965 too.

The idea is to make better use of GLSLOptimizeConservatively.
Currently TGSI must ignore the flag until all functions have been
inlined by the GLSL IR opts. Since NIR can do function inlining we
can drop the post linking opts calls for Gallium drivers that use
NIR and just use the faster NIR opts instead. The patches to do
this will come in a follow-up series since it requires some
refactoring and testing and I wanted to get this out for review.

For i965 this series enables GLSLOptimizeConservatively for a nice
boost in compile times and very little change in shader-db.