Move Project::subConfigWidgets to BuildConfiguration

Change-Id: Idf58ebbb02e9cd0ab4ff7e74fbed17250e274693
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>

src/plugins/cmakeprojectmanager/cmakebuildconfiguration.h

@@ -52,6 +52,7 @@ public:
     ~CMakeBuildConfiguration();
 
     ProjectExplorer::BuildConfigWidget *createConfigWidget();
+    QList<ProjectExplorer::BuildConfigWidget *> subConfigWidgets();
     QString buildDirectory() const;
 
     void setBuildDirectory(const QString &buildDirectory);