Android: Warn if sdkmanager could not be run

Add a line in the error checking for "SDK manager runs"

Fixes: QTCREATORBUG-22626
Change-Id: I63f783b376056a28c106bad1ce8c874acf6897f2
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/android/androidsdkmanager.h

@@ -78,6 +78,8 @@ public:
     void reloadPackages(bool forceReload = false);
     bool isBusy() const;
 
+    bool packageListingSuccessful() const;
+
     QFuture<QString> availableArguments() const;
     QFuture<OperationOutput> updateAll();
     QFuture<OperationOutput> update(const QStringList &install, const QStringList &uninstall);