RFC: xfwm4: drop legacy KDE systray emulation

[Matt Connell]

On Wed, 2022-10-19 at 15:22 +0200, Enrico Weigelt, metux IT consult
wrote:
> Is there anybody out there who still has practical use for it ?

Does this refer to the "Status Tray Plugin" for the panel, or is that
something native?

> It's not built unless explicitly enabled

I'm running XFCE on Gentoo, and I don't find a USE flag for either
xfwm4 or nor xfce4-panel.  Am I looking in the wrong place?

I'd like to make sure we aren't talking about the same things, because
I rely heavily on the status tray plugin.