Fix backup req bug in h2

src/brpc/policy/http2_rpc_protocol.cpp

@@ -1449,10 +1449,10 @@ private:
 
 void H2UnsentRequest::DestroyStreamUserData(SocketUniquePtr& sending_sock,
                                             Controller* cntl,
-                                            int /*error_code*/,
+                                            int error_code,
                                             bool /*end_of_rpc*/) {
     RemoveRefOnQuit deref_self(this);
-    if (sending_sock != NULL && cntl->ErrorCode() != 0) {
+    if (sending_sock != NULL && (cntl->ErrorCode() != 0 || error_code != 0)) {
         CHECK_EQ(cntl, _cntl);
         std::unique_lock<butil::Mutex> mu(_mutex);
         _cntl = NULL;