Debugger: Use a somewhat less intrusive hack for 'start at main'

Change-Id: Ie649a4a11c88f3686cd6ed1e73f34c7c78fd0e13
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/debuggerruncontrol.h

@@ -79,6 +79,8 @@ public:
 
     void appendSolibSearchPath(const QString &str);
 
+    static void setBreakOnMainNextTime();
+
 signals:
     void aboutToNotifyInferiorSetupOk();