Old drm1 drivers now completely useless

[Francois Tigeot]

The lowest mesa version now available in FreeBSD ports has just been
switched to 9.1.7:
https://svnweb.freebsd.org/ports?view=revision&revision=371035

Since Mesa 8.0+ has dropped support for drm1 drivers, these drivers
are now completely useless.

They were only used to provide 3D OpenGL acceleration.

The following directories contain their sources in the DragonFly
kernel:

- /usr/src/sys/dev/drm/mach64
- /usr/src/sys/dev/drm/mga
- /usr/src/sys/dev/drm/r128
- /usr/src/sys/dev/drm/savage
- /usr/src/sys/dev/drm/sis
- /usr/src/sys/dev/drm/tdfx

I'm thinking of removing them from the git repository before the next
release.

-- 
Francois Tigeot