Merge branch 'PHP-5.6'

* PHP-5.6:
  Optimize ZEND_POW (Rouven Weßling)
  gcov: tentative fix for broken coverage data after fix for opcache coverage slightly hackish, but works. The idea is that we want to give priority to .gcda files in .libs dirs vs the files in the upper level dir

Conflicts:
	ext/opcache/ZendAccelerator.h