Welcome XFCE 4.16 to the FreeBSD ports tree!

Upstream announce: https://xfce.org/about/news/?post=1608595200

This XFCE release dropped support for GTK2 plugins and also dropped
GTK2 from all components.

Due to this some panel plugins and libraries will be removed since
they cannot compile anymore:

• print/xfce4-print
• x11/xfce4-quicklauncher-plugin
• x11/xfce4-wmdock-plugin
• x11-toolkits/libxfce4gui

These further components also fail to build or work and are being
marked BROKEN, deprecated and marked for removal:

• science/xfce4-equake-plugin
• x11/xfce4-embed-plugin
• deskutils/orage
• deskutils/xfce4-volumed [1]

deskutils/xfce4-notes-plugin will be also marked BROKEN, but there
is active development in it's upstream repository and a fixed release
is expected soon.

deskutils/xfce4-generic-slider will also be marked broken, since
it fails to compile. [2]

Thanks also to riggs, Olivier Duchateau <duchateau.olivier@gmail.com>
and the people in Approved and Reviewed lines below for help and
contributions.

Reviewed by: woodsb02
Approved by: sergey.dyatko@gmail.com (maintainer) [1],

			ehaupt [2]

Differential Revision: https://reviews.freebsd.org/D27846