net/nmsg: Upgrade to version 1.0.1

• nmsgtool: Fix use-after-free bug in statistics debugging (seen on Debian 10).
• nmsg/base/dnsqr.c: Initialize len in dnsqr_hash to squash code-checker uninitialized warning.
• Fix assert conditions with side effects for builds with -DNDEBUG

Sponsored by: Farsight Security, Inc.