Send haveResult() with an empty QString instead of a an empty C strin…

…g. Avoids ambiguity with the version of this signal which takes a boolean arg. Coverity defect 703725

mythplugins/mytharchive/mytharchive/fileselector.cpp

@@ -357,7 +357,7 @@ void FileSelector::cancelPressed()
     if (m_selectorType == FSTYPE_FILELIST)
         emit haveResult(true);
     else
-        emit haveResult("");
+        emit haveResult(QString());
     Close();
 }