Sync with FreeBSD:
- mktime() already does daylight savings.
- Explain the format of the at.allow and at.deny files in detail.
- mdoc improvements.
- Use MAXLOGNAME - 1 instead of UT_NAMESIZE.
- Do not pretend there is something like '/etc/utmp'.
- Add the SUSv3 -l option to at. This is an alias for atq. Allow job ids
to be specified on the command line for which information should be
reported.
- Document the fact that at(1) is run through cron(8). This affects the
granularity of the at queue runs.
- Organize #includes.
- Remove the -V [version number] option.
- Implement the POSIX 1003.1-2001 -r and -t options in at(1).
- Warns cleanup and diff reduction from FreeBSD.
- Remove some unsafe function calls from the signal handlers.
- Fix privileges macros.
Obtained-from: FreeBSD