[Bug target/53383] Allow -mpreferred-stack-boundary=3 on x86-64

[hpa at zytor dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383

--- Comment #7 from H. Peter Anvin <hpa at zytor dot com> 2012-05-18 15:23:05 UTC ---
We can't use the SSE parts of the ABI anyway in the kernel, and I sure hope
that -mno-sse (or perhaps -mcmodel=kernel, but that would be ugly) prevents
those from being generated.

Yes, it's an ABI violation, but it's a very necessary one...