runconfig: consolidate createConfigurationWidget implementations

Most derived classes used essentially identical 'return 0;'
implementations. Use a base class implementation doing that instead.

Change-Id: I99727ac2230a5d9f168b4b0eb5927f8efff44e64
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

src/plugins/projectexplorer/runconfiguration.cpp

@@ -574,6 +574,11 @@ IRunConfigurationAspect *IRunControlFactory::createRunConfigurationAspect()
     return 0;
 }
 
+RunConfigWidget *IRunControlFactory::createConfigurationWidget(RunConfiguration *)
+{
+    return 0;
+}
+
 /*!
     \class ProjectExplorer::RunControl
     \brief Each instance of this class represents one item that is run.