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

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

Set machine correctly on ARM. This allows universe to use the correct world
when building each kernel.

Reviewed by: imp

Instead of using sysarch() to store-retrieve the tp, add a magic address,
ARM_TP_ADDRESS, where the tp will be stored. On CPUs that support it, a cache
line will be allocated and locked for this address, so that it will never go
to RAM. On CPUs that does not, a page is allocated for it (it will be a bit
slower, and is wrong for SMP, but should be fine for UP).
The tp is still stored in the mdthread struct, and at each context switch,
ARM_TP_ADDRESS gets updated.

Suggested by: davidxu

Move KERNPHYSADDR and KERNVIRTADDR from std.i80321 to std.iq31244.
Use the correct KERNPHYSADDR.

Import partial support for the IQ31244 eval board (i80321 CPU). IQ80321 might
work out of the box too, but I have no hardware to test.
It works well enough to go multiuser. Network works, SATA does not, as I have
no drive to test.
Thanks to Intel for sending such a board.

Obtained from: NetBSD