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.

- Note existence of -m option.
- Note that -s applies to rule keyword, only, by adding usage text
  specifically for the `rule` and `ruleset` keywords.

Don't go into any further detail in usage(..) -- it's best that one
reads the manpage to get a better idea of how things work as there are
a number of different option-specific keywords and arguments, as well
as some rule grammar.

MFC after:	1 week
Sponsored by:	Dell EMC Isilon

strings and cp is not.  Fix logic in the original code and eliminate
core dumps on lines without '\n'.

PR:		bin/98905
Submitted by:	Fabian Keil
MFC after:	1 week

return for getopt() and comparing to -1, ditto with fgetc() and EOF,
and using the kg_nice value from <sys/user.h>

Submitted by: Stefan Farfeleder <stefan@fafoe.narf.at>
Reviewed by: obrien, bde (a while back)
Tested lightly on: ppc, i386, make universe

<sys/param.h>) for definition of <stdint.h> macros.

of a rule specification is a single dash (``-''), rules are read from
the standard input and the rest of the specification is ignored.

administrator to define certain properties of new devfs nodes before
they become visible to the userland.  Both static (e.g., /dev/speaker)
and dynamic (e.g., /dev/bpf*, some removable devices) nodes are
supported.  Each DEVFS mount may have a different ruleset assigned to
it, permitting different policies to be implemented for things like
jails.

Approved by:	phk