Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC r236991:

Final whitespace trim.

Submitted by: imp
Approved by: marius
Obtained from: Netflix

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Add some checks to ensure that Capsicum is behaving correctly, and add some
more explicit comments about what's going on and what future maintainers
need to do when e.g. adding a new operation to a sys_machdep.c.

Approved by: mentor(rwatson), re(bz)

We may split today's CAPABILITIES into CAPABILITY_MODE (which has
to do with global namespaces) and CAPABILITIES (which has to do with
constraining file descriptors). Just in case, and because it's a better
name anyway, let's move CAPABILITIES out of the way.

Also, change opt_capabilities.h to opt_capsicum.h; for now, this will
only hold CAPABILITY_MODE, but it will probably also hold the new
CAPABILITIES (implying constrained file descriptors) in the future.

Approved by: rwatson
Sponsored by: Google UK Ltd

Continue to introduce Capsicum capability mode:

White list sysarch calls allowed in capability mode; arguably, there
should be some link between the capability mode model and the privilege
model here. Sysarch is a morass similar to ioctl, in many senses.

Submitted by: anderson
Discussed with: benl, kris, pjd
Sponsored by: Google, Inc.
Obtained from: Capsicum Project
MFC after: 3 months

Make md_tp a register_t not a void *. This will keep us from
accidentally dereferencng it and might be one fewer things to change
if arm64 happens...

Submitted by: rwatson's question on irc...

style(9) cleanup.

Implement two new sysarch for arm, ARM_GET_TP and ARM_SET_TP, to work around
the lack of tls on arm.

Add MD syscalls to sync the icache and to drain the write buffer.

Obtained from: NetBSD

Remove unused includes.

Spotted out by: pjd

Import FreeBSD/arm kernel bits.
It only supports sa1110 (on simics) right now, but xscale support should come
soon.
Some of the initial work has been provided by :
Stephane Potvin <sepotvin at videotron.ca>
Most of this comes from NetBSD.