Debugger: Fix attaching via QtSingleApplication.

In case qtcdebugger sends a command to an already running
instance of Qt Creator (Windows).

Reviewed-by: hjk
Task-number: QTCREATORBUG-2814

src/plugins/debugger/debuggerplugin.h

@@ -80,6 +80,7 @@ public:
     QVariant configValue(const QString &name) const;
     void setConfigValue(const QString &name, const QVariant &value);
     void updateState(DebuggerEngine *engine);
+    virtual void remoteCommand(const QStringList &options, const QStringList &arguments);
 
     QIcon locationMarkIcon() const;
     void activateDebugMode();