Valgrind: Port to Qt5-style connect

Change-Id: If5f36bb262b932b60133d4301ab614311ce1feee
Reviewed-by: hjk <hjk@theqtcompany.com>

src/plugins/valgrind/memcheckengine.cpp

@@ -84,8 +84,8 @@ bool MemcheckRunControl::startEngine()
 
 void MemcheckRunControl::stopEngine()
 {
-    disconnect(&m_parser, SIGNAL(internalError(QString)),
-               this, SIGNAL(internalParserError(QString)));
+    disconnect(&m_parser, &ThreadedParser::internalError,
+               this, &MemcheckRunControl::internalParserError);
     ValgrindRunControl::stopEngine();
 }