The ng_h4 module was disconnected 13 years ago when the tty later was
locked by Ed. It completely fails to compile, and has a number of false
positives for Giant use. Remove it for lack of interest. Bluetooth has
largely (completely?) moved on from bluetooth over UART transport.

OK'd by:		emax
Sponsored by:		Netflix
Differential Revision:	https://reviews.freebsd.org/D31846

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

struct ifnet if_oqdrops.

Some netgraph modules used ifqueue w/o ifnet. Accounting of queue drops
is simply removed from them. There were no API to read this statistic.

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.

malloc(9) flags within sys.

Exceptions:

- sys/contrib not touched
- sys/mbuf.h edited manually

MFC after:	3 months

Reconnect ng_h(4) back to the build.

Reviewed by:	kensmith
Approved by:	re (kensmith)
MFC after:	1 month

Approved by:	re (rwatson)

specific privilege names to a broad range of privileges.  These may
require some future tweaking.

Sponsored by:           nCircle Network Security, Inc.
Obtained from:          TrustedBSD Project
Discussed on:           arch@
Reviewed (at least in part) by: mlaier, jmg, pjd, bde, ceri,
                        Alex Lyashkov <umka at sevcity dot net>,
                        Skip Ford <skip dot ford at verizon dot net>,
                        Antoine Brodin <antoine dot brodin at laposte dot net>