Valgrind: Add a ValgrindRunner member to the ValgrindToolRunner base

... instead of having one in each derived class.

Change-Id: Icd121ce46b1d161bd2d59eaeaad8363528dc3c23
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/valgrind/memcheckengine.h

@@ -55,12 +55,10 @@ signals:
 private:
     QString progressTitle() const override;
     QStringList toolArguments() const override;
-    ValgrindRunner *runner() override;
 
     void startDebugger();
     void appendLog(const QByteArray &data);
 
-    ValgrindRunner m_runner;
     const bool m_withGdb;
 };