Remove Project::dependsOn(), it's never called

I don't remember why I did leave it alone in the reafctoring some years
ago, but surely it serves no purpose.

Change-Id: Idf920faf3f8f7128cd410501f2c3748e100dfbfb
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>

src/plugins/genericprojectmanager/genericproject.cpp

@@ -430,11 +430,6 @@ IProjectManager *GenericProject::projectManager() const
     return m_manager;
 }
 
-QList<Project *> GenericProject::dependsOn()
-{
-    return QList<Project *>();
-}
-
 QList<BuildConfigWidget*> GenericProject::subConfigWidgets()
 {
     QList<BuildConfigWidget*> list;