Segfault with PHP 5.6

[weitzman]

Myself and tlittlefield both saw segfaults when hitting index-perf.php with PHP 5.6. php55 works fine.

Also, would be helpful if there was a clear error when xhprof extension is not present.

[LionsAd]

Thanks for the bug report. I will look into that!

[LionsAd]

index-perf.php is supposed to also work when xhprof is not installed. This is useful for ab style testing without having apache in between, but the raw PHP performance, which is useful to avoid xhprof related performance characteristics.