QLocalSocket: Print value OperationError on debug output

Pick-to: 5.15
Change-Id: Ib3e38e8c0a46b2070eca1e65f081b2d6d2774020
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

src/network/socket/qlocalsocket.cpp

@@ -547,6 +547,9 @@ QDebug operator<<(QDebug debug, QLocalSocket::LocalSocketError error)
     case QLocalSocket::UnknownSocketError:
         debug << "QLocalSocket::UnknownSocketError";
         break;
+    case QLocalSocket::OperationError:
+        debug << "QLocalSocket::OperationError";
+        break;
     default:
         debug << "QLocalSocket::SocketError(" << int(error) << ')';
         break;