Import svn-1.8.0 final
Import subversion-1.8.1 into vendor staging area.
Import svn-1.8.4, which includes fixes for both security and merge
handling.
Import subversion-1.8.5
Vendor import svn-1.8.8
Vendor import svn-1.8.9
Add support for SOUND_MIXER_INFO IOCTL, used by gstreamer.

Submitted by:	Dmitry Luhtionov <dmitryluhtionov@gmail.com>
MFC after:	2 weeks
MFV r269223:

Change dn->dn_dbufs from linked list to AVL tree.

Illumos issues:
  4873 zvol unmap calls can take a very long time for larger datasets

MFC after:	2 weeks
MFV r269224:

Increase default ARC buf_hash_table size.  When typical block size is small,
the hash table could be too small, which would lead to long hash chains and
limit performance for cached reads.

A new loader tunable, vfs.zfs.arc_average_blocksize, have been added which
allows users to override the default assumption of average (typical) block
size.  Old default was 65536 (64 KiB) and new default is 8192 (8 KiB).

Illumos issue:
    5034 ARC's buf_hash_table is too small

MFC after:	2 weeks
Fix build with gcc
Remove SC_DFLT_FONT option. vt(4) don't use it.

Suggested by:	emaste
Sponsored by:	The FreeBSD Foundation
Remove unused option.
Fix comment typo in r269052.

Submitted by:	Daniel O'Connor
Add VOP_GETVOBJECT.9 to obsolete files, un-xref.

X-MFC with:	r269160
Correct typo in comment
Fix yet another comment typo in r269052.
Garbage collect couple of unused fields from struct ifaddr:
- ifa_claim_addr() unused since removal of NetAtalk
- ifa_metric seems to be never utilized, always a copy of if_metric
Remove one-time use macros which check for the vnode lifecycle.  More,
some parts of the checks are in fact redundand in the surrounding
code, and it is more clear what the conditions are by direct testing
of the flags.  Two of the three macros were only used in assertions.

In vnlru_free(), all relevant parts of vholdl() were already inlined,
except the increment of v_holdcnt itself.  Do not call vholdl() to do
the increment as well, this allows to make assertions in
vholdl()/vhold() more strict.

In v_incr_usecount(), call vholdl() before incrementing other ref
counters.  The change is no-op, but it makes less surprising to see
the vnode state in debugger if interrupted inside v_incr_usecount().

Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
mdoc: sort sections.
Silence mandoc lint.