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

Sync program's usage() with manpage's SYNOPSIS.

#include <unistd.h> for getopt() and friends.

PR: 36130
Approved by: mike

Use getopt() to reject options (asa has none), and to the "--" end of options
marker. Exit non-zero if we cannot open one of the input files. Update
standards conformance and exit status statements in manual page.

PR: 36130
Approved by: mike

Remove __P,
Don't prototype main(),
C89-style function declarations,
char **argv -> char *argv[] for main()

PR: 36130
Approved by: mike

style(9): remove space between function name and opening parentheses,
sort variables, NULL is the null-pointer constant, remove unnecessary
braces.

PR: 36130
Approved by: mike

Add the POSIX.2 asa utility, which interprets FORTRAN carriage-control
characters.

PR: 36130
Approved by: mike
Obtained from: NetBSD