Sync newsyslog(8) with FreeBSD's current code.

Sync newsyslog(8) with FreeBSD's current code.

New things:

* Re-ordering of the rotate/signal steps. First, rotate all files which
  need to be rotated and then send a single signal to each daemon that
  needs to be notified. This way, each daemon will only be signaled once
  instead of once per file.

* Allow /var/log to be a symbolic link.

* -d option for specifying an alternate root for log files.

* -D option for debugging purposes.

* -N option to suppress log file rotation (intended to be used in
  conjunction with -C and -CC).

* Bug fixes and minor improvements.

Note: FreeBSD's r1.107 of newsyslog.c was not brought in as it generates
      a warning in DragonFly instead of fixing one.