number before attempting to load the Macintosh partition info. If the
first 32-bits of block 0 contain the BSD disklable magic number, treat
it as a NetBSD disklabel.
When loading the Macintosh partition map, check the first 32 partitions
for the root, usr, and swap partitions--instead of the first 8. Still
only allows 8 total partitions for NetBSD use.