[Intel-gfx] [RFC] cherry-pick texture indirections fix to intel-2008-q3

[Eric Anholt]

I'd like to get this fix into intel-2008-q3.  It seems many games are built
to take full advantage of 4 texture indirections, as multiple vendors happened
to support just that many, and we were failing at it.  However, I haven't
actually had a chance to run any of those games (commercial stuff under wine,
mostly), so I'd really like to have some additional review for merging.
Ideally the reviewer has access to 945 specs and can see if what I changed it
to really matches what they interpret from the specs, but even comparing
against ARB_fp specs for sanity couldn't hurt.