net/ndisc6: Update 1.0.7 => 1.0.8, take maintainership

Changelog:
https://git.remlab.net/gitweb/?p=ndisc6.git;a=blob;f=NEWS;hb=refs/tags/v1.0.8

Replace gettext with gettext-runtime: the port does not use the tool
components - it only links with libintl.
Reduce the number of install command calls.

PR: 288829
Co-authored-by: Vladimir Druzenko <vvd@FreeBSD.org>