Valgrind: Clean error view on run control startup again

Fixes a recently introduced regression.

Change-Id: Ia36977df87906c320527123f84dd1a347768b06c
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

src/plugins/valgrind/valgrindengine.cpp

@@ -67,6 +67,7 @@ ValgrindRunControl::ValgrindRunControl(RunConfiguration *runConfiguration, Core:
 
 void ValgrindRunControl::start()
 {
+    emit starting();
     FutureProgress *fp = ProgressManager::addTimedTask(m_progress, progressTitle(), "valgrind", 100);
     fp->setKeepOnFinish(FutureProgress::HideOnFinish);
     connect(fp, &FutureProgress::canceled,