x11/lumina-core: Fix LScreensaver password check

lumina-checkpass was disabled in the previous build, causing the
screensaver to unlock on any input rather than just the correct pw.

Also removed xscreensaver dep, replaced by LScreensaver.

LPanel patch is a hack to redraw the panel after screen resize. Makes
Lumina usable, though still not pretty, in a VirtualBox guest with
guest additions. Still needs wallpaper redraw.

PR: 262320
Approved by: lbartoletti