Fix gssapi/gssapi_krb5.h after Heimdal 1.5.1 import.

Reviewed by:	dfr
Make various fixes to <stdatomic.h>.

- According to the standard, memory_order is a type. Use a typedef.

- atomic_*_fence() and atomic_flag_*() are described by the standard as
  functions. Use inline functions to implement them.

- Only expose the atomic_*_explicit() functions in kernel space. We
  should not use the short-hand functions, as they will always use
  memory_order_seq_cst.
Convert this piece of code to use C11 atomics.

As mentioned before, we should at least aim to have one piece of code in
both user space and kernel space that uses C11 atomics, to get some
coverage. This piece of code can be migrated trivially, so it's a good
candidate.
Make atomic_fetch_add() and atomic_fetch_sub() work for pointers with GCC 4.2.

According to the standard, atomic_fetch_*() has to behave identical to
regular arithmetic. This means that for pointer types, we have to apply
the stride when doing addition/subtraction.

The GCC documentation seems to imply this is done for __sync_*() as
well. Unfortunately, both tests and Googling seems to reveal this is not
really the case. Fix this by performing the multiplication with the
stride manually.
truss: recognize O_DIRECTORY, O_EXEC, O_TTY_INIT and O_CLOEXEC

MFC after:	3 days
acct: reduce code duplication by using acct_disable as cleanup for
failed kproc_create

MFC after:	1 week
Use && rather than ; when success of previous job matters.
Correct some grammar.
acct: create a special plimit object and set it for exiting processes
instead of allocating new one each time

All limits are set to RLIM_INFINITY which sould be ok (even though we
care only about RLIMT_FSIZE in this case).

MFC after:	1 week
Grammar tweaks for locking.9

Reviewed by:	jhb
Approved by:	hrs (mentor)
In generic_bs_map(), use kmem_alloc_nofault() instead of kmem_alloc(), as we
only need virtual addresses.

Submitted by:	alc
Decrypt magic numbers - define names for fields of Generic Timer's CNTKCTL reg.

Submitted by:	Ruslan Bukin <br@bsdpad.com>
Add "ether" and "link" to ifconfig_alias{es,N}.
Replace some spaces to tab.
killall: add -q flag to suppress error message when no processes are matched

Man-page text provided by wblock.

PR:		bin/30542
Submitted by:	Tony Finch <dot@dotat.at> (original version)
MFC after:	1 week
libc: Access _sigintr more efficiently.

The variable _sigintr is not exported via the version script; therefore,
tell the compiler that no indirection (to allow interposition) is needed.
When decoding SLEB128, make sure sign extension is performed for
64-bit integers.

MFC after:	3 days
Enable kernel-specific code for FreeBSD also on other systems that use
the kernel of FreeBSD.

Reviewed by:	pjd
Add INET6.
Fix issues with zeroing and fetching the counters, on x86 and ppc64.
Issues were noted by Bruce Evans and are present on all architectures.

On i386, a counter fetch should use atomic read of 64bit value,
otherwise carry from the increment on other CPU could be lost for the
given fetch, making error of 2^32.  If 64bit read (cmpxchg8b) is not
available on the machine, it cannot be SMP and it is enough to disable
preemption around read to avoid the split read.

On x86 the counter increment is not atomic on purpose, which makes it
possible for the store of the incremented result to override just
zeroed per-cpu slot.  The effect would be a counter going off by
arbitrary value after zeroing.  Perform the counter zeroing on the
same processor which does the increments, making the operations
mutually exclusive.  On i386, same as for the fetching, if the
cmpxchg8b is not available, machine is not SMP and we disable
preemption for zeroing.

PowerPC64 is treated the same as amd64.

For other architectures, the changes made to allow the compilation to
succeed, without fixing the issues with zeroing or fetching.  It
should be possible to handle them by using the 64bit loads and stores
atomic WRT preemption (assuming the architectures also converted from
using critical sections to proper asm).  If architecture does not
provide the facility, using global (spin) mutex would be non-optimal
but working solution.

Noted by:  bde
Sponsored by:	The FreeBSD Foundation