x11-wm/cwm: Update to 7.9

ChangeLog:

2026-05-19: Tenth public release 7.9 of portable cwm.

Changes made between OpenBSD 7.6 and 7.7:

• Grab the pointer against the root window instead of the client we're attempting to move and/or resize; prevents XNextEvent() from blocking on a client that might have been moved to a Withdrawn state.

Changes made between OpenBSD 7.7 and 7.8:

• Add cwmrc(5) window-snap-center function.

Changes made between OpenBSD 7.8 and 7.9:

• Have cwm(1) handle Meta release as a separate mod key.

MFH: 2026Q2
(cherry picked from commit 21a6c2722772c4996c6ed5026a7584b4ea0296f9)