getopt(3): recognize option:: as GNU extension for "optional options".

Also ANSIfy a function declaration.

While here update the OpenBSD patch level in getopt_long.c as we
already have the corresponding change.

Obtained from:	NetBSD
MFC after:	2 weeks
Don't take filedesc lock in fdunshare().

We can read refcnt safely and only care if it is equal to 1.

If it could suddenly change from 1 to something bigger the code would be
buggy even in the previous form and transitions from > 1 to 1 are equally racy
and harmless (we copy even though there is no need).

MFC after:	1 week
Merge intermediate OpenBSD v1.25 changes (almost identical to ours)
to reduce diff and bump OpenBSD patch level to v1.26.

MFC after:      2 weeks
cxgbe(4): Update the bundled T4 and T5 firmwares to versions 1.11.27.0.

Obtained from:	Chelsio
MFC after:	3 days
Change suggestion how to set MAKESYSPATH as broken incremental build
workaround. Magic ".../share/mk" (search directories up to /)
does not work for f.e. /usr/src/gnu/lib/libgcc because the path
inside is starting from /usr/obj hierarchy and ends up in
/usr/share/mk, not in the /usr/src/share/mk where src.opts.mk is.
IMHO proper fixing of incremental build is needed urgently.
Fix a couple of bugs on amd64 when fetching probe arguments beyond the
first five for probes entered through a UD fault (i.e. FBT probes).

Specifically, handle the fact that dtrace_invop_callsite must be
16 byte-aligned and thus may not immediately follow the call to
dtrace_invop() in dtrace_invop_start(). Also fetch register arguments and
the stack pointer through a struct trapframe instead of a struct reg.

PR:		191260
Submitted by:	luke.tw@gmail.com
MFC after:	3 weeks
Tidy up fd-related functions called by do_execve

o assert in each one that fdp is not shared
o remove unnecessary NULL checks - all userspace processes have fdtables
and kernel processes cannot execve
o remove comments about the danger of fd_ofiles getting reallocated - fdtable
is not shared and fd_ofiles could be only reallocated if new fd was about to be
added, but if that was possible the code would already be buggy as setugidsafety
work could be undone

MFC after:	1 week
Fix some bugs when fetching probe arguments in i386. Firstly ensure that
the 4 byte-aligned dtrace_invop_callsite can be found and that it
immediately follows the call to dtrace_invop(). Secondly, fix some pointer
arithmetic to account for differences between struct i386_frame and illumos'
struct frame. Finally, ensure that dtrace_getarg() isn't inlined. It works
by following a fixed number of frame pointers to the probe site, so inlining
breaks it.

MFC after:	3 weeks
Restore the check for non-NULL dmatag in sndbuf_free.

The sound drivers that use own buffer management can use sndbuf_setup
and not do any busdma allocation, so the driver will end up with the
managed buffer but no valid dma map and tag for it. Avoid calling
bus_dmamem_free in such cases.

Reported by: ache
Missed in review by: kan
Catch up with r186809, correct comments.
Use correct names for the flags.  MAP_ENTRY_GROWS_* have the same
numerical values as MAP_STACK_GROWS_*, but the former is for entries'
eflags, while the later for the cow argument of vm_map_insert().

Submitted by:	alc
Add FPU_KERN_KTHR flag to fpu_kern_enter(9), which avoids saving FPU
context into memory for the kernel threads which called
fpu_kern_thread(9).  This allows the fpu_kern_enter() callers to not
check for is_fpu_kern_thread() to get the optimization.

Apply the flag to padlock(4) and aesni(4).  In aesni_cipher_process(),
do not leak FPU context state on error.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Add documentation for the fpu_kern(9) interfaces.

Many thanks to jmg for reviewing the (previous version) of the text
and providing grammar and content fixes.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
use .Mt to mark up email addresses consistently (part3)

PR:		191174
Submitted by:	Franco Fichtner  <franco at lastsummer.de>
use .Mt to mark up email addresses consistently (part4)

PR:		191174
Submitted by:	Franco Fichtner  <franco at lastsummer.de>
use .Mt to mark up email addresses consistently (part6)

PR:		191174
Submitted by:	Franco Fichtner <franco at lastsummer.de>
Several small fixes (typos, grammar, mdoc).
Fix markup and grammar.