x11/libX11: Update to 1.8.9

Release notes for 1.8.8: https://lists.x.org/archives/xorg-announce/2024-March/003492.html
Release notes for 1.8.9: https://lists.x.org/archives/xorg-announce/2024-April/003501.html

Differential Revision: https://reviews.freebsd.org/D44795
Reviewed by: bapt
PR: 278122
Sponsored by: Beckhoff Automation GmbH & Co. LG