MFC r326276:

various: general adoption of SPDX licensing ID tags.

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.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Treat the '-' as meaning standard input.

Obtained from: NetBSD

Make nl(1) build with WARNS=6.

Obtained from: NetBSD

The NetBSD Foundation has granted permission to remove clause 3 and 4
from their software.

Obtained from: NetBSD

Use getline() instead of fgets(). This enables nl(1) to handle
arbitrarily long lines and embedded NULs. The new functionality is
nugatory, but adding it is a simple way to improve the exposure of
getline() in -CURRENT.

Avoid 'bogus' uninitialized warning by initializing rather than
playing cute games. It is much simpler, clearer and easier to follow
and understand. Besides, gcc4 likes it better.

Remove unused variables.

Add support for multibyte characters.

Tidy up usage message.

Remove local prototypes for main().

The XCU issue 5 requirement of accepting the file operand intermingled
with options has been withdrawn in issue 6, to which nl(1) now conforms.

style(9): use errx() where appropriate instead of fprintf() + exit().

style(9): use err() instead of perror() + exit().

remove __P

Removed duplicate VCS ID tags, as per style(9).

Add nl(1)

PR: 27078
Obtained from: NetBSD