[Test] Show file and line number in debug output

tests/TestMain.cpp

@@ -26,6 +26,7 @@ int main(int argc, char *argv[])
     app.setApplicationName(QStringLiteral("kdenlive"));
     std::unique_ptr<Mlt::Repository> repo(Mlt::Factory::init(nullptr));
     qputenv("MLT_TESTS", QByteArray("1"));
+    qSetMessagePattern(QStringLiteral("%{file}:%{line} – %{message}"));
     Core::build(QString(), true);
     MltConnection::construct(QString());
     pCore->projectItemModel()->buildPlaylist();