ProjectExplorer: Add a RunControl::supportsReRunning setter

Removes one reason to derive from base RunControls (specifically
ValgrindRunControl).

Change-Id: I81e32a49ef30e79ee7e7b53a54021eaaba43453a
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/valgrind/valgrindengine.h

@@ -47,7 +47,6 @@ public:
 
     void start() override;
     void stop() override;
-    bool supportsReRunning() const override { return false; }
 
     QString executable() const;