Merge branch 'PHP-5.5'

* PHP-5.5:
  don't optimize script if it's not going to be cached
  Reimplemented OPcache restart trigger. Now, if memory or hash are full the restart is scheduled only in case the amount of wasted memory is above opcache.max_wasted_percentage. Otherwise OPcahce continue serving the following requests using already cached files, but doesn't try to add new files (the cache is full anyway).