add xf86-video-qxl to support spice displays in QEMU

[markshank]

This guy has built the code from upstream and tested it: FreeBSD 12.2 missing xorg qxl video driver

And he has submitted a bug report, patch and interacted with developers: x11-drivers/xf86-video-qxl deprecated/deleted, yet upstream source builds on freebsd 12.2

@mszoek "wow... if it is really just patching the port makefile, I could easily build that into airyx"

Reference original discussion on Discord