util: try much harder to set DAZ flag

util: try much harder to set DAZ flag

While so far this only causes some harmless test failures, there's lots more
cpus with DAZ. All 64bit capable ones can do it (particularly relevant for
AMD cpus as they supported sse3 very very late) but if really necessary we
can check support for that for real with some more magic.
(In fact just about ANY cpu with sse2 can support DAZ, I believe the only
exception are first gen P4 (Willamette) and from those only early steppings
which can't do it it's almost like intel forgot to add it... - a real pity
though docs say you can't just try to set it as they will throw a GPF.)
While this was meant to address https://bugs.freedesktop.org/show_bug.cgi?id=67672
it does not fix it. Most likely the tests need fixing as I don't think
there's any guarantee about denorm handling in the reference math library
functions if the flags aren't set to standard values. Nevertheless enabling
DAZ on all cpus which can do it should be the right thing to do.

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>