For BERI on NetFPGA assume HZ=100 by default.

Remove the uart support in favour of a "jtag-uart" interface imitation
providing a much simpler interface, directly exported to the host,
allowing the toolchain to be shared with BERI on Altera. [1]

Submitted by:	Jong Hun HAN (jong.han cl.cam.ac.uk) [1]
MFC after:	2 weeks
Simplify how we build MACHINE_ARCH. There are 3 options that may be set
however only arm, armeb, armv6, and soon armv6hf will be used.
Create a root dataset so that /root is outside of the boot environment.

Discussed with:	dteske on sysinstall@
MFC after:	1 month
Update 20140302
In particular this brings schema validation support.
Update to 20140321
This brings schema validation

MFC after:	1 week
sfxge: limit software Tx queue size.

Previous implementation limits put queue size only (when Tx lock can't
be acquired), but get queue may grow unboundedly which results in mbuf
pools exhaustion and latency growth.

Submitted by:	Andrew Rybchenko <Andrew.Rybchenko at oktetlabs.ru>
Sponsored by:	Solarflare Communications, Inc.
Fix build with libucl 20140321
Don't lose track of the KTR entries copied from 'ktr_buf_init[]' to the
dynamically allocated 'ktr_buf[]'.

The memcpy arranges 'ktr_buf[]' such that the latest KTR entry is at
'KTR_BOOT_ENTRIES - 1'.