avoid segfaults

ext/spl/spl_iterators.c

@@ -929,7 +929,7 @@ static inline spl_dual_it_object* spl_dual_it_construct(INTERNAL_FUNCTION_PARAME
 		case DIT_RecursiveRegExIterator: {
 			char *regex;
 			int len, poptions, coptions;
-			pcre_extra *extra;
+			pcre_extra *extra = NULL;
 
 			intern->u.regex.flags = 0;
 			if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "Os|l", &zobject, ce_inner, &regex, &len, &intern->u.regex.flags) == FAILURE) {