Securityupdate to 4.9.2:

Changelog:
https://codex.wordpress.org/Version_4.9.2
https://wordpress.org/news/2018/01/wordpress-4-9-2-security-and-maintenance-release/

PR: 225243
Submitted by: Mikhail Timofeev <9267096@gmail.com> (maintainer)
Approved by: mentors (implicit)
MFH: 2018Q1
Security: c04dc18f-fcde-11e7-bdf6-00e04c1ea73d