Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

update 'sio' with 'uart' and apply related changes.

Fix the PICOBSD kernel configs. They're now converted to use
Peter's new format, and I'd added hints files for each.

The build process uses the PICOBSD.hints file as well as the config,
and additionally builds with -DNO_MODULES. The build process
probably needs to be converted to use the 'buildkernel' method
instead of running config itself.

The kernels now compile. I've not been able to test the crunch
process however because it used the vn driver and there are no
/dev/vn device nodes under devfs yet. Maybe someone else could
give it a go.