If I get it right,  `Z_SET_ISREF_P(matches)`/`Z_UNSET_ISREF_P(matches)` are only needed when we call the userspace version.

If so, we can move these macros to `phalcon_preg_match()` — which will be more friendly to a developer if they forgot to surround the calls with Z_(UN)SET_ISREF_P macros.