_NETBSD_SOURCE as this makes cross building from older/newer versions of
NetBSD harder, not easier (and also makes the resulting tools 'different')
Wrap all required code with the inclusion of nbtool_config.h, attempt to
only use POSIX code in all places (or when reasonable test w. configure and
provide definitions: ala u_int, etc).
Reviewed by lukem. Tested on FreeBSD 4.9, Redhat Linux ES3, NetBSD 1.6.2 x86
NetBSD current (x86 and amd64) and Solaris 9.
Fixes PR's: PR#17762 PR#25944
fstype checking, and back-end "ffs" support.
- Consistently use at least uint32_t for blocknumbers (vs. int / long / ...)
- Consistently use uintXX_t instead of u_intXX_t.
- Move various duplicated prototypes into "installboot.h"
tsutsui