omni authored Dec 16, 2021 and Ariadne Conill committed Jan 23, 2022

- Xen looks for /usr/share/qemu-xen/qemu but xen-qemu installed to
  /usr/share/qemu, and would also collide the community/qemu aport
- use amove
- keep the default libexecdir
- install desktop entry as /usr/share/applications/qemu-xen.desktop
- build pv-grub stubdoms and qemu-traditional based device model,
  disabled by default since 4.16