Patch from Dirk Behme

Please see mail thread '[patch] Cleanup of head.S?' from 25 Feb 2003. Let us remove the third part now. The mapping set by this code is done already.

The comment of rmk was

'I suspect we can kill (3) without hurting stuff that's merged into the
-rmk tree, although I'm sure there's a reason it existed.  I'll have
to check my mail archives, but I think there was a machine that required,
but it appears not to be merged.'

So, let's try and see if somebody cries...