FreeBSD_HEAD_i386 - Build #844 - Fixed

FreeBSD_HEAD_i386 - Build #844 - Fixed:

Build information: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_i386/844/
Full change log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_i386/844/changes
Full build log: https://jenkins.FreeBSD.org/job/FreeBSD_HEAD_i386/844/console

Change summaries:

286774 by mav:
2618 arc.c mistypes in the comments

Reviewed by: Jason King <jason.brian.king_at_gmail.com>
Reviewed by: Josef Sipek <jeffpc_at_josefsipek.net>
Approved by: Richard Lowe <richlowe_at_richlowe.net>
Author: Bart Coddens <bart.coddens_at_gmail.com>

illumos/illumos-gate_at_fc98fea58e89224f6f13d7fae246d6cb5dfa35ea

286773 by hselasky:
Improve the realtime properties of USB transfers for embedded systems
like RPI-B and RPI-2.

Description of problem:
USB transfers can process data in their callbacks sometimes causing
unacceptable latency for other USB transfers. Separate BULK completion
callbacks from CONTROL, INTERRUPT and ISOCHRONOUS callbacks, and give
BULK completion callbacks lesser execution priority than the
others. This way USB audio won't be interfered by heavy USB ethernet
usage for example.

Further serve USB transfer completion in a round robin fashion,
instead of only serving the most CPU hungry. This has been done by
adding a third flag to USB transfer queue structure which keeps track
of looping callbacks. The "command" callback function then decides
what to do when looping.

MFC after:		2 weeks

286770 by mav:
Fix r286766 build with debug.