Heads up for LinuxKPI updates to 12-STABLE

Hi

As with recent 13-CURRENT, we're pushing some updates that might break
build of drm modules temporarily on 12-STABLE. One of those changes is
moving lindebugfs.ko from ports to base. If you're building your kernel
with MODULES_OVERRIDE, don't forget to include it since it is required
by drm drivers that use linuxkpi.

A new drm-fbsd12.1-kmod port for 12-STABLE (later includes also
12.1-RELEASE) will be created. The goal is to provide support for
hardware that is supported by Linux 5.0, in FreeBSD 12.1.

In an emergency, drivers for 12-STABLE can (hopefully) be built directly
from github here https://github.com/FreeBSDDesktop/kms-drm (drm-v4.16 or
drm-v5.0 branches), once today's series of commits are in.

Any testing on 12-STABLE is welcome. drm-v5.0 is still WIP but should be
quite usable.

Cheers!