ARM GPUs

I have been working on trying to get accelerated graphics to work for
ARM Ltd GPUs in NetBSD.

There are separate Linux and Mesa codebases for each of the Mali-400
(lima) and Mali-Txxx (panfrost) GPUs.

Have run out of things to try and am not getting any response from core
people either with comments on diffs or with any discussion on how to
start getting this into the tree so that I can get more eyes looking at
it.

Lima on a Pinebook seems to be doing something, I get FPS measurement
output from the test app that I'm using, but the screen on my Pinebook
is broken so I can't tell if it is displaying anything.

Panfrost on a Pinebook Pro doesn't do anything, the first shader sent to
the GPU just times out. The main difference to how this runs on Linux is
the MMU setup code, I can't see anything wrong with this.