Xfce 4.20

Hi,

I don't know, if someone is currently working on the forthcoming 4.20 
release.

As I need libxfce4windowing for one of my port, I made an "unofficial 
repository" [1].

Notable changes:
- Update WWW entry (instead of xfce.org → URL of gitlab.xfce.org path) 
in several core components
- Switch to meson when it is available
- Add 2 entries in Mk/Uses/xfce.mk (devel/xfce4-dev-tools, and 
x11/libxfce4windowing)
- Update dependencies (add wayland unconditionally, remove USE_GNOME= 
intltool when it is not required)
- Add wayland in x11/xfce4-screenshooter-plugin

A made documentation [2], to build core components and test.

I do not intent to submit patch when the final release will be available.

I also noticed, sysutils/xfce4-settings does not build with clang.

[1] https://codeberg.org/olivierd/freebsd-xfce4
[2] https://codeberg.org/olivierd/freebsd-xfce4/wiki

-- 
olivier