QMediaNetworkPlaylistProvider: Upon error parsing, stop parsing.

When an error is found parsing a playlist, stop
parsing. This will also prevent the emission of
the "loaded" signal when the parser finishes.

Task-number: QTBUG-40513
Change-Id: Ia814864d0d546806219993f0b727761d5d4e7903
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>

src/multimedia/playback/qmedianetworkplaylistprovider.cpp

@@ -90,6 +90,8 @@ void QMediaNetworkPlaylistProviderPrivate::_q_handleParserError(QPlaylistFilePar
         break;
     }
 
+    parser.stop();
+
     emit q->loadFailed(playlistError, errorMessage);
 }