[PATCH] x86: include OSXSAVE in x86-64-v3 level

[Florian Weimer]

* Noah Goldstein via Libc-alpha:

> We should also update isa-level.h
> https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/x86/isa-level.h;h=06f6c9663e76d4a48efb8fbfdb707cc5045f47dc;hb=HEAD
>
> I think the compiler flag for it is `__XSAVE__`

I don't think so.  We don't need XSAVE support, we need OSXSAVE support,
and that's not actually a compiler or even purely a CPU thing.

Thanks,
Florian