[Mesa-dev] ac/radeonsi/radv: share more compiler code

[Dave Airlie]

This is the prep work patches for storing the compiler in TLS
for radv. I'm revising how I think that should end up looking
in light of Marek's review, but I think we could at least land
this chunk of the setup code first. I've moved some of these
around since the last posting, and renamed a few things,
and written some better commit logs.

Dave.