Make Qt4ProejctManager::MakeStep::run multithreading safe

Change-Id: I416360d35681d2721878cb9fefd861d6e1f209b4
Reviewed-on: http://codereview.qt-project.org/5451
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

src/plugins/projectexplorer/abstractprocessstep.cpp

@@ -152,6 +152,11 @@ ProjectExplorer::IOutputParser *AbstractProcessStep::outputParser() const
     return m_outputParserChain;
 }
 
+bool AbstractProcessStep::ignoreReturnValue()
+{
+    return m_ignoreReturnValue;
+}
+
 /*!
     \brief If ignoreReturnValue is set to true, then the abstractprocess step will
     return success even if the return value indicates otherwise.