Pull in r174303 from upstream gcc trunk (by Jason Merrill):

  PR c++/48211
  * name-lookup.h (cp_class_binding): Make base a pointer.
  * name-lookup.c (new_class_binding): Adjust.
  (poplevel_class): Adjust.

This fixes a potential segfault when compiling gold, a part of the
devel/binutils port, with gcc.  See also the upstream bug report:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48211

Thanks to Jason Merrill, Tom Callaway and Red Hat legal for approving
the use of this patch under the GNU GPL, version 2 or later.

MFC after:	1 week
Swap resource count scopes for used/available space.

Used count should be reported as per-LUN, while available should not.

MFC after:	1 week
Add MLINKs for all functions described in the libxo manpages.
Add to CTL support for threshold notifications for file-backed LUNs.

Previously it was supported only for ZVOL-backed LUNs, but now should work
for file-backed LUNs too.  Used value in this case is a space occupied by
the backing file, while available value is an available space on file
system.  Pool thresholds are still not implemented in this case.

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
Document r275481 changes.

MFC after:	2 weeks
This is the SCTP specific companion of
https://svnweb.freebsd.org/changeset/base/275358
which was provided by Hans Petter Selasky.