So...

PR 6152 claimes that seperate-I&D-cache machines with UVM fail to obey
gdb breakpoints correctly.

I've committed a fix for this, based on what Michael Hitch proposed, but
with slightly different interface. In-tree are:

- Machine independent part
- Amiga MD part (tested)
- Atari, Mac68k, HP300 (not yet tested)

I've send my change to his diff back to Michael for inspection and testing.

I can do the other 68k ports (after some sleep).
I could even do and test arm32 (do we have an otherwise working gdb there?)
I think PowerPC should be affected, too, but I don't have a machine to test
on.

Portmasters: if you think that your port needs this, please (tell somebody to)
implement. The interface is:

pmap.h:

#define PMAP_NEED_PROCWR
void pmap_procwr((struct proc *p, vaddr_t start, size_t len));

implementation to your taste.

Regards,
	Ignatios Souvatzis