Switch to the new common bus_space-v6.c, remove the local one.
Switch to the new common bus_space-v6.c, remove the local one.
Do not build aicasm with the cross-tools/kernel-toolchain, instead add a
proper kernel-tools step/target modeled after the world build-tools stuff.

This is a re-do of r257730 which was backed out in r257734, but this time
it's one byte smaller... a leftover trailing backslash resulted in a .for
loop with no rules, so no compiler stuff got built and later steps built
with the wrong toolset.