[virglrenderer-devel] second posting, sampler array refactor, compute, fb no attach, glsl4.30

[Dave Airlie]

This is the second posting of the series, the first two are unrelated cleanups,
they can be reviewed/pushed separately if needed.

Changes since last posting:
Expose all grid/block sizes in the capability limits
Add a new robust buffer access feature bit to enable GL 4.3
Add r-b tag to the fb no attachment

I think we should be able to land the GLES3.1/3.2, GL4.3 work in mesa in time
for 18.2 which will be nice.

Dave.