Make ZVOL writes in device mode support IO_SYNC flag.

MFC after:	1 month
Improve cache control support, including DPO/FUA flags and the mode page.

At this moment it works only for files and ZVOLs in device mode since BIOs
have no respective respective cache control flags (DPO/FUA).

MFC after:	1 month
Sponsored by:	iXsystems, Inc.
ptrace handling first update, optional finer grained permissions based on request flags
Rename new to newval in inline asm code, to avoid clashes with C++ new.
Also rename cmp to cmpval just to keep the asm variable names similar to
the C variable names.
Add support for Mode Page Policy (0x87) VPD page.
Revert r269474. Special keyboard combinations should be handled by separate
sysctls.
Oops, missed piece of r271311.
- Add missing "
- Sort sections
Minor mdoc nit.
Report that DPO and FUA bits are supported after r271311.
Avoid unlocking unlocked mutex in RCTL jail code.  Specific test case
is attached to PR.

PR:		193457
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Merge branch 'hardened/current/ptrace' into hardened/current/unstable
Fix ctld(8) to not forget to send TargetPortalGroupTag and TargetAlias
when the initiator skips security negotiation.  This fixes interoperability
with Xtend SAN initiator.

PR:		193021
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Use keys_add_int() where appropriate.  No functional changes.

Sponsored by:	The FreeBSD Foundation
Don't cross mount boundaries when cleaning tmp files.

Mounting something in /tmp such as a build jail with nullfs mounts for
some directories can result in very surprising results the next day.

MFC after:	2 weeks
Relnotes:	yes
Whitespace nit.

MFC after:	1 week
HBSD: Revert "HARDENING: randomize pid numbers"

This reverts commit af29a61e5ca6c5f0b8ed9926a3d54ea8dcd68813.

The randompid property can changed only with sysctl, and not with
tunable. If I change it's value in the code before the init started,
then the init picked up wrong PID number.

Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
PAX SEGVGUARD: include opt_pax.h to include segvguard

Signed-off-by: Oliver Pinter <oliver.pntr@gmail.com>
Merge branch 'hardened/current/master' into hardened/current/hardening
Merge remote-tracking branch 'origin/master' into hardened/current/master

Conflicts:
	share/man/man9/sysctl.9 (fixed)