Update to nmh-1.0.2:

Documentation update providing current support channels.
No show-stopping bugs fixed, just lots of nits.

Changes to the actual port:

Simplify handling of PREFIX.
Use autoconf.
Use DOT_LOCKING, not FLOCK_LOCKING. (IMPORTANT)
Tweak DESCR to make it more obvious that this is an MUA.

PR: 15423
Submitted by: maintainer