Update to 6.9.4

• Update pkg-message
• While I'm here, remove duplicate PLIST_SUB which is already handled by OPTIONS_SUB=yes

Changes: https://github.com/nodejs/node/blob/master/doc/changelogs/CHANGELOG_V6.md

		https://nodejs.org/en/blog/release/v6.9.4/

PR: 215776
Submitted by: Bradley T. Hughes <bradleythughes@fastmail.fm> (maintainer)