x11-toolkits/wlc: Mark as deprecated

x11-toolkits/wlc has been deprecated upstream, deprecate it in the ports
tree and set expiration date.

https://github.com/Cloudef/wlc/commit/6e2c49bf5789115bf33873f3e0ebe603c8e7725d

PR: 232767
Reported by: jbeich