Replace BuildConfigWidge with NamedWidget

They have a identical interface.

Change-Id: Ia626496fbaffedefff6ee20b958cd505085d89f7
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/qt4projectmanager/qt4buildconfiguration.cpp

@@ -184,7 +184,7 @@ void Qt4BuildConfiguration::emitBuildDirectoryChanged()
     }
 }
 
-BuildConfigWidget *Qt4BuildConfiguration::createConfigWidget()
+NamedWidget *Qt4BuildConfiguration::createConfigWidget()
 {
     return new Qt4ProjectConfigWidget(this);
 }