compositor: Do not prefer XPresent on AMD hardware

Bug: 16716

Prefer GLX for vblank on AMD, until the issue is fixed in the Xorg DDX.

See-also: https://gitlab.freedesktop.org/xorg/driver/xf86-video-amdgpu/merge_requests/52


Signed-off-by: Olivier Fourdan <fourdan@xfce.org>