Bring in gcc r128087 to add support for _Unwind_Backtrace on ARM. This is
prior to the licence change so is under the GPLv2.
Implement _Unwind_GetIP and _Unwind_GetIPInfo as functions as that is what
we expect on FreeBSD. The implementation is based on the existing macros.
Fix bug introduced in rewrite of keg_free_slab in -r251894.
The consequence of the bug is that fini calls are not done
when a slab is freed by a call-back from the page daemon.
It went unnoticed for two months because fini is little used.

I spotted the bug while reading the code to learn how it works
so I could write it up for the next edition of the Design and
Implementation of FreeBSD book.

No MFC needed as this code exists only in HEAD.

Reviewed by: kib, jeff
Tested by:   pho
Implement pmap_advise().
Fixes for DTrace on PowerPC:

- Implement dtrace_getarg()
- Sync fbt with x86, and fix a typo.
- Pull in the time synchronization code from amd64.
Only add the backlight device if it actually exists in OF.

MFC after:	1 week
Add support to the ARM platform specific section types.
Fix two build failures for non-tb configurations, UP [2] and when using gas [1].

Reported by:	andreast [1], bf [2]
Sponsored by:	The FreeBSD Foundation
Add support for the GCC binary integer constants extension.

This is required to build the i965 backend with newer versions of mesa.

Original patch from Joerg Wunsch in GCC Bug 23479, under the GPLv2;
also taken from there in OpenBSD.

Obtained from:	gcc 4.3 (rev. 125346; GPLv2)
MFC after:	5 days
libc: Always use our own copy of sys_errlist and sys_nerr (.so only).

This ensures strerror() and friends continue to work correctly even if a
(non-PIE) executable linked against an older libc imports sys_errlist (which
causes sys_errlist to refer to the executable's copy with a size fixed when
that executable was linked).

The executable's use of sys_errlist remains broken because it uses the
current value of sys_nerr and may access past the bounds of the array.

Different from the message "Using sys_errlist from executables is not
ABI-stable" on freebsd-arch, this change does not affect the static library.
There seems no reason to prevent overriding the error messages in the static
library.
Add support for postponing VirtIO virtqueue interrupts

Partial support for the EVENT_IDX feature was added a while ago,
but this commit adds an interface for the device driver to hint
how long (in terms of descriptors) the next interrupt should be
delayed.

The first user of this will be used to reduce VirtIO net's Tx
completion interrupts.
Add optional VirtIO device method for post-attach notifications

This is called after the parent device (ie virito_pci) has
completed the device attachment/initialization.
Sync VirtIO net device header file from recent Linux
Import multiqueue VirtIO net driver from my user/bryanv/vtnetmq branch

This is a significant rewrite of much of the previous driver; lots of
misc. cleanup was also performed, and support for a few other minor
features was also added.
Fix the build with CTLFEDEBUG, broken by unmapped I/O support changes.
Fix targbh crash on XPT_IMMED_NOTIFY error during attach.
Fix SES_ENABLE_PASSTHROUGH kernel option, unexpectedly broken during driver
overhaul.

MFC after:	3 days
Bring legacy CAM target implementation back into API/KPI-coherent and even
functional state.  While CTL is much more superior target from all points,
there is no reason why this code should not work.

Tested with ahc(4) as target side HBA.

MFC after:	2 weeks
Fix a compiler warning about signed vs unsigned compare.
Add the device ID for a new flavor of FTDI serial adapter (model 232EX).