Fix compilation error in row0ins.c

row0ins.c:1437:6: error: ISO C90 forbids mixed declarations and code [-Werror=declaration-after-statement]
enum wsrep_key_type key_type = WSREP_KEY_EXCLUSIVE;
^

storage/innobase/row/row0ins.c

@@ -1434,9 +1434,11 @@ row_ins_check_foreign_constraint(
 				}
 
 				if (check_ref) {
-					err = DB_SUCCESS;
 #ifdef WITH_WSREP
 					enum wsrep_key_type key_type = WSREP_KEY_EXCLUSIVE;
+#endif /* WITH_WSREP */
+					err = DB_SUCCESS;
+#ifdef WITH_WSREP
 					if (upd_node != NULL) {
 						key_type = WSREP_KEY_SHARED;
 					} else {