[Bug target/77270] Flag -mprftchw is shared with 3dnow for -march=k8

[nightstrike at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77270

--- Comment #5 from nightstrike <nightstrike at gmail dot com> ---
(In reply to Uroš Bizjak from comment #2)
> The problem is in the fact that for -march=native, the driver will pass
> -mno-prfchw, since the relevant bit is not present in cpuid flags.

I'm a little confused.  -march=native gets it right.  It's -march=k8 that gets
it wrong.  Does your patch make -march-k8 do the right thing now?