MFC: r262135

Add $FreeBSD$.
MFC: r262136

Remove the 3rd clause ("advertising clause") of the BSD license as
permitted by the University of Berkeley on July 22, 1999.

Reviewed by:	imp
MFC r262142:

   In ue_attach_post_task(), initialize curvnet to vnet0 before calling if_attach().
   Before this patch, curvnet was NULL.
   When the VIMAGE kernel option is enabled, this eliminates
   kernel panics when USB ethernet devices are plugged in.

PR: 183835
Submitted by: Hiroo Oono <hiroo.ono at gmail dot com>
MFC r261774 by feld:

	Add caveat to zpool manpage indicating that we do not automatically activate
	hot spares. This should be MFC'd to all STABLE branches.

	Upon the availability of zfsd, the zpool manpage on relevant branches should
	be updated to remove this caveat and document hot spare's reliance on zfsd.

Requested by:	feld
MFC r262125:

In sys/dev/usb/controller/uss820dci.c, similar to r261977, fix a warning
about uss820dci_odevd being unused, by adding it to the part that
handles getting descriptors.

Reported by:	loos
Reviewed by:	hselasky
MFC r262309:

Fix a race between kern_proc_{o,}filedesc_out and fdescfree leading
to use-after-free.

fdescfree proceeds to free file pointers once fd_refcnt reaches 0, but
kern_proc_{o,}filedesc_out only checked for hold count.
MFC r262310:

Move the part in bsd.own.mk that sets -Wno-c++11-extensions for clang to
bsd.sys.mk, where it really belongs.  This also causes the flag to get
added when clang is *not* the default system compiler, but is still
used, e.g. by setting WITH_CLANG_IS_CC manually.
MFC r262467: sh: Add -h option to SYNOPSIS

Reviewed by:	jilles
MFC: r261773

In acline_init(), initialize ac_line to SRC_UNKNOWN.  Previously
this could lead to the -n option effectively being ignored (in case
ac_line happened to be 0 aka SRC_AC), or other undefined behaviour.

PR:		169779
Submitted by:	Alex Gonzalez <loox at e-shell.com>
Reviewed by:	jhb