The getty variants out there (including agetty) require an relative path
to the /dev directory as argument. This is really odd but we want to be
backwards-compatible to them so we allow this, too.
--vt now accepts:
* A positive number which is internally converted into /dev/ttyXY
* A string that does not start with '/' or '.' which is interpreted
relative to /dev as /dev/%s
* Everything else is interpreted as path
This option still selects only the TTY on seat0. On all other seats we do
not use controlling TTYs.
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>