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/cmakeprojectmanager/cmakeproject.cpp

@@ -496,11 +496,6 @@ CMakeTarget *CMakeProject::activeTarget() const
     return static_cast<CMakeTarget *>(Project::activeTarget());
 }
 
-QList<ProjectExplorer::Project *> CMakeProject::dependsOn()
-{
-    return QList<Project *>();
-}
-
 QList<ProjectExplorer::BuildConfigWidget*> CMakeProject::subConfigWidgets()
 {
     QList<ProjectExplorer::BuildConfigWidget*> list;