Add DRM lease support to agl-compositor

From gerrit review of [Change 26112 drm-lease: Add weston DRM lease integration
https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-devel/+/26112
 
Marius Vlad
>> Can this done for agl-compositor as well? You'll probably need some way to determine if libweston has been built with drm-lease feat or not.
This is a longer discussion on its own, you'll need to experiment a bit a see if there's "something" that give you that.
 
Damian Hobson-Garcia
> I will make a JIRA ticket for the agl-compositor support.

I think that the biggest concern would be that the drm_lease_name member of the weston_drm_backend_config struct is present, since without that the build will fail. If that is merged upstream, I think that a version check on libweston should be sufficient for this aspect. I that case maybe its best to keep that off the agl-compositor master branch until DRM lease support lands in libweston. Maybe keeping it in meta-agl-devel for now.

If DRM lease support is not enabled in libweston, trying to open a lease will fail in the same way as trying to open a non-existent DRM device with the --drm-device flag. So maybe doing something like is done for HAVE_REMOTING, where just the necessary library dependencies are checked might work for this case.