Remove all support for gcc < 4.2.
This one is almost killable too. Outside of ce(4), we use this in one location: i386 resumectx(). And it isn't clear (to me) that we need the oddball calling convention in that location. Maybe we do.
ce(4) doesn't matter: it will define it if it isn't already defined. So we can safely ignore it. :)
I'm not sure what resumectx() does on i386,... I may investigate though...
But in any event, I was going to do an audit of all these defines to see what's still used as a followup.