Make annma happy :-)

My previous idea of a shaded out "en_US" worked in all cases bar one, where the user is on a system with a system language not en_US and they want to set to use en_US as their KDE language.

I tried all sorts of other ways of doing this but they proved too confusing, so it's back to the old way of en_US being a normal choice with no special handling even though it lets the user do silly things.

This also means I can switch back to a now fixed KActionSelector.