V2 [PATCH] x86: Use _rdtsc intrinsic for HP_TIMING_NOW

[Florian Weimer]

* H. J. Lu:

> +   NB: Use __builtin_ia32_rdtsc directly since including <x86intrin.h>
> +   is very slow with GCC 6.  */

Thanks for the patch.

It fixes the issue, but the comment is wrong: I see the same slowdown
with GCC 8.