re: sun3 kernels don't work in netbsd 7, 8 or -current.

i have commited fixes to -current to make sun3 work again.
i'e had to remove a fair bit of stuff from GENERIC that,
but there's only about 150kb of free space so i wanted to
leave some growth room.

i also had to reduce some other kernel components to
reclaim enough kernel virtual space to run.

so, current works again now.  thanks to maya and jdc for
helping confirm the kernel size and with other issues.

i'll port these back to netbsd-7 and netbsd-8.


.mrg.