Merge pull request #78137 from akien-mga/4.0-regex-nullptr-free

[4.0] regex: Add nullptr check in `_regex_free`, needed with PCRE2 10.42

modules/regex/regex.cpp

@@ -40,7 +40,9 @@ static void *_regex_malloc(PCRE2_SIZE size, void *user) {
 }
 
 static void _regex_free(void *ptr, void *user) {
-	memfree(ptr);
+	if (ptr) {
+		memfree(ptr);
+	}
 }
 
 int RegExMatch::_find(const Variant &p_name) const {