Update to a newer snapshot of stable Mesa. Includes a fix for hangs with
RV200 Radeons (thanks Dave Airlie!) , fixes for software fallbacks, the usual
pile of little conformance and other bugfixes, and fixing the hang on first lock
grab on AMD64 (that was a really lame bug). Host the distfile on freefall as
well until public_distfiles propagates.
PR:  ports/75731
Submitted by:  pb