Objective-C category methods prohibit safe unloading of dynamic
libraries / plugins statically linked to Qt. Although they can be called in
convenient way they can be replaced with standalone functions without
noticeable drawback.
Remove unused qt_validModesForFontPanel category method.
Remove empty NSStatusItem (Qt) category.
Task-number: QTBUG-59884
Change-Id: I69503a115b1177623da91c67b62d72e56f43ffcf
Reviewed-by: Jake Petroules <jake.petroules@qt.io>