There is too much #ifdef DEBUG stuff cluttering locore, really. While some of

There is too much #ifdef DEBUG stuff cluttering locore, really. While some of
it had sense in the early days of the sparc64 port, this code has bitrotten
and is getting in the way. Time for a visit to the Attic.

This removes:
- interrupt handling debug code (forcing hz = 1, probably broken since years).
- unused or too invasive DEBUG code which noone will ever use in this state.
- #if 0 code blocks which have been this way since locore.s revision 1.1 and
  will never get enabled.

ok kettenis@