[PATCH] x86-64: Add sinf with FMA

[Nick Alcock]

On 4 Dec 2017, H. J. Lu uttered the following:

> On Skylake, bench-sinf reports performance improvement:
>
>             Before        After         Improvement
> max        153.996       100.094           54%
> min        8.546         6.852             25%
> mean       18.1223       14.4616           25%
>
> Any comments?

Do we have any benchmark runs on older processors? They're not remotely
obsolete: Intel is still selling Broadwell server parts, and the vast
majority of SSE2-capable parts out there at present are not as new as
Skylake.

Are we penalizing them? (I'd guess not, but it would be nice to know.)