Replace legacy zval_dtor() by zval_ptr_dtor_nogc() or even more specialized destructors.

zval_dtor() doesn't make a lot of sense in PHP-7.* and it's used incorrectly in some places.
Its occurances should be replaced by zval_ptr_dtor() or zval_ptr_dtor_nogc(), or even more specialized destructors.

Author: dstogov

php_ibase_udf.c

@@ -302,7 +302,7 @@ static void call_php(char *name, PARAMDSC *r, int argc, PARAMDSC **argv)
 			}
 		}
 
-		zval_dtor(&callback);
+		zval_ptr_dtor_str(&callback);
 
 		/* return whatever type we got back from the callback: let DB handle conversion */
 		switch (Z_TYPE(return_value)) {