Add feature for usr.sbin/newsyslog.c: accept human unit suffix for size fileds in configuration file.

[Rin0913]

In previous versions of newsyslog, the size had to be configured in KB, which is too small for modern computers.

With this update, we can use three types of units: K, M, and G. For example,

# logfilename          [owner:group]    mode count size when  flags [/pid_file] [sig_num]
/var/log/all.log                        600  7     *    @T00  J
/var/log/auth.log                       600  7     1000 @0101T JC
/var/log/console.log                    600  5     100M *     J
/var/log/cron                           600  3     1G   *     JC
/var/log/daemon.log                     644  5     1000K @0101T JC

[lwhsu]

I think we can use expand_number(3) from libutil?

[lwhsu]

And we may also need to update manual page to indicate that we can use human readable format.

[Rin0913]

The manual will look like this: