wxgtk31: wayland dependency

[Karsten Pedersen]

>
> Hmm, seems so, but I don't have xorg-minimal installed 
> 
> $ pkg info xorg-\*
> xorg-fonts-truetype-7.7_1
> xorg-server-1.20.11,1
> 

Ah I see, you have a lighter install of Xorg than me. OK I have
been looking around at what is really pulling Wayland in and it
seems that Gtk itself does too (at least by default) :/

https://svnweb.freebsd.org/ports/head/x11-toolkits/gtk30/
https://www.freebsd.org/cgi/ports.cgi?query=^gtk3-3.24.27