* restored the zone>block stuff
* generalized the support for more-than-1-block bitmaps to also deal
with big inodes maps in small blocks
* improved pexit() to printf-like syntax; also replaced pexit() with
err() or errx() where there are no reference to proto lines
* unified the allocation of blocks to all use alloc_block() instead
of raw malloc half of the time
* removed the V2_ d2_ etc. prefixes which are obscure and obsolete
While here, also
* used new-form definitions, and closer to KNF style in general
* used often-built-ins such as mem* or strncpy where relevant
* pruned a fair amount of constants which are irrelevant
Thanks to Thomas V. and Lionel who did a good amount of work with the
cross-compilation stuff and made that change to be much smoother.