MFC	r270256:
Always check the limits of array index variables before using them.

Obtained from:	DragonFlyBSD
MFC r270519:

Fix "make checkdpadd" for lib/libc when MK_SSP != no

 Add LIBSSP_NONSHARED to bsd.libnames.mk and append LIBSSP_NONSHARED to DPADD in
 lib/libc when MK_SSP != no

 Approved by: rpaulo (mentor)
 Phabric: D675 (as part of a larger diff)
 PR: 192728
Mention NFS and kernel iSCSI optimizations.
Document volmode ZVOL property addition.
Document ZVOLs got BIO_DELETE support.
Add FreeBSD/ARM notes.

These do not have corresponding revision numbers, since
the updates took place over a large span of revisions,
not one revision in particular.

Submitted/prepared by:	ian
Sponsored by:	The FreeBSD Foundation
Fix typo.

Submitted by:	Hugo Lombard <hal@elizium.za.net>
Use <acronym> and <literal> in a few places where needed.
Minor rewording to r264732 entry.

Sponsored by:	The FreeBSD Foundation
We do not differentiate the SMP from GENERIC kernel anymore,
so remove mention of it.

Sponsored by:	The FreeBSD Foundation
Minor rewording to a few sections.

Sponsored by:	The FreeBSD Foundation
FDP style nits.

Sponsored by:	The FreeBSD Foundation
Minor wording changes.

Sponsored by:	The FreeBSD Foundation