I've changed sparc port's value of KERNBASE to 0xf0000000 (was 0xf8000000).

This should provide more kernel virtual address space to accomodate
large buffer caches on machines that have the physical memory to
back it.

Last week, I have changed the kvm library and the bootblocks to not
depend on a compiled-in KERNBASE constant (but if you have not yet
rebuilt the libkvm dependent utilities, you'll have to do so now).

There's also a work-around in locore so that kernels linked at the
new base address can continue to be booted from old bootblocks
(only relevant to DDB kernels, anyway).

-pk