dialog: Do not crash with previous table version (11)

This patch ensures OpenSIPS doesn't crash if the "dialog.script_flags"
column is still of INT type (previous DB schema, before OpenSIPS 3.4).

(cherry picked from commit a1b2738)

modules/dialog/dlg_db_handler.c

@@ -722,7 +722,7 @@ static int load_dialog_info_from_db(int dlg_hash_size)
 			}
 
 			/* script flags */
-			if (!VAL_NULL(values+19)) {
+			if (!VAL_NULL(values+19) && VAL_TYPE(values+19) != DB_INT) {
 				GET_STR_VALUE(flag_list, values, 19, 0, 0);
 				dlg->user_flags = flag_list_to_bitmask(&flag_list,
 					FLAG_TYPE_DIALOG, FLAG_DELIM, 1);