Don't reissue in-flight commands.

Approved by:	neel (co-mentor)
Fix and improve exception tracing:
1.  Name the kernel option XTRACE instead of EXCEPTION_TRACING
2.  Put support functions in ia64/ia64/xtrace.c
3.  Make it work with SMP by giving each CPU its own buffer
4.  Save 16 key registers in the buffer for every exception
5.  In ia64_handle_intr() and trap() transfer the trace record
    to the KTR trace buffer using CTRx() and with some basic
    information for now
6.  Use a tunable to anble tracing and stop tracing as soon as
    we enter the debugger

Room for improvements:
1.  Transferring exception-relevant information to KTR
2.  Add a sysctl to enable/disable tracing
Fix GENERIC build.
vm_page_grab() and vm_pager_get_pages() can drop the vm_object lock,
then threads can sleep on the pip condition.
Avoid to deadlock such threads by correctly awakening the sleeping ones
after the pip is finished.
swapoff side of the bug can likely result in shutdown deadlocks.

Sponsored by:	EMC / Isilon Storage Division
Reported by:	pho, pluknet
Tested by:	pho
Only invoke fasttrap hooks for traps from user mode, and ensure that they're
called with interrupts enabled. Calling fasttrap_pid_probe() with interrupts
disabled can lead to deadlock if fasttrap writes to the process' address
space.

Reviewed by:	rpaulo
MFC after:	3 weeks
Now, after r263102 we have ifi_oqdrops in if_data, restore printing of
output queue drops in netstat(1).

No driver, neither kernel fills this field in if_data, yet.

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.
Add counter for Tx errors returned from if_transmit.

Submitted-by:	Boris Misenov <Boris.Misenov@oktetlabs.ru>
Sponsored by:	Solarflare Communications, Inc.
When exporting ifnet via sysctl, add ifqueue(9) drop count to the
ifi_oqdrops. This is a temporary workaround until ifqueue(9) vanishes.

While here, remove the pointless ifi_vhid assignment. It has
sense only when we are exporting ifaddrs, not ifnets.

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.
Added sysctl kern.maxfiles increase test, do not use /etc/passwd for tests
and use volatile sig_atomic_t for signal handler variable.

Reviewed by:	 asomers (previous version)
Sponsored by:	EMC / Isilon storage division
Expand tabs that sneaked in into spaces.

Problem introduced by r263227.  Spotted by Alan Somers.
Migrate tools/regression/usr.bin/make/ to the new tests layout.

Note that these tests are for fmake, not bmake, and thus they are not
installed nor run when bmake is selected (the default).  Yes, I have
wasted a *ton* of time on moving tests for no real reason other than
ensuring they are not left behind.

But maybe, just maybe, it was not work in vain: the majority of these
tests also work with bmake and the few that don't may point at broken
stuff.  For example, the tests for the "archive" feature do not work
with bmake, but bmake's manpage and source tree seem to imply that they
should.  So... to be investigated later; need to poke sjg@.
Add Makefiles missed in r263346.

Grrr, I wish svn clearly displayed files not yet added when about to commit.
Make the array pointed to by AT_PAGESIZES auxv properly aligned.

Also, remove the expression which calculated the location of the
strings for a new image and grown over the time to be
non-comprehensible.  Instead, calculate the offsets by steps, which
also makes fixing the alignments much cleaner.

Reported and reviewed by:	alc
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Fix comments.

Sponsored by:	EMC / Isilon Storage Division
Migrate tools/regression/usr.bin/pkill to the new tests layout.

Interestingly, the pkill tool lives in bin, not usr.bin.  Haven't bothered
to check if this is because the tool moved or because the tests were
originally added in the wrong place.
Make the priv test program exit with non-zero if any failures are detected.

And, mind you, this already returns a failure :-/
errx prepends the program name to the message; don't do it by hand.
Make the error message more clear.

Sponsored by:	The FreeBSD Foundation
Include strings.h so that bpf_filter.c can be built in userland.

This is to bring in a definition for bzero(3), which in turn allows the
tests in tools/regression/bpf/ to build again.
Add my humble request for reviews before nanobsd changes happen.