Reserve some elements

Change-Id: Iceef4e9a6f213a747045db3b06a5608d77652f98
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/libs/qmldebug/baseenginedebugclient.cpp

@@ -193,6 +193,7 @@ void BaseEngineDebugClient::messageReceived(const QByteArray &data)
         int count;
         ds >> count;
         QList<EngineReference> engines;
+        engines.reserve(count);
         for (int ii = 0; ii < count; ++ii) {
             EngineReference eng;
             ds >> eng.m_name;