Merge remote-tracking branch 'origin/4.8'

Conflicts:
	src/plugins/winrt/winrtdevicefactory.cpp

Change-Id: I33b8697e2ebf2bea051d7f1144449e0743ee16a5

src/plugins/help/helpviewer.cpp

@@ -135,6 +135,10 @@ bool HelpViewer::launchWithExternalApp(const QUrl &url)
         const QUrl &resolvedUrl = helpEngine.findFile(url);
         if (!resolvedUrl.isValid())
             return false;
+        // Workaround QTBUG-71833
+        // QHelpEngineCore::findFile returns a valid url even though the file does not exist
+        if (resolvedUrl.scheme() == "about" && resolvedUrl.path() == "blank")
+            return false;
 
         const QString& path = resolvedUrl.path();
         if (!canOpenPage(path)) {