gallivm: disable avx512 features

gallivm: disable avx512 features

We don't target this yet, and some llvm versions incorrectly enable it based
on cpu string, causing crashes.
(Albeit this is a losing battle, it is pretty much guaranteed when the next
new feature comes along llvm will mistakenly enable it on some future cpu,
thus we would have to proactively disable all new features as llvm adds them.)

This should fix https://bugs.freedesktop.org/show_bug.cgi?id=94291 (untested)

Tested-by: Timo Aaltonen <tjaalton@ubuntu.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com
CC: <mesa-stable@lists.freedesktop.org>