[PATCH] x86: Avoid vector/r16-r31 registers and memcpy/memset in mcount_internal

[Florian Weimer]

* Andreas K. Huettel:

> OK with review, thanks.
>
> The impact of -mgeneral-regs-only -mno-apxf is kind of obvious.
>
> Does -fno-tree-loop-distribute-patterns also impact the register
> selection or is this a subsequent higher level optimization?

It prevents the compiler from recognizing memcpy and memset patterns and
replacing them with calls to our functions, which would use vector
registers as well.

Thanks,
Florian