Rototill code to determine the tty. For Linux, we now look up the

Rototill code to determine the tty.  For Linux, we now look up the
tty device in /proc/pid/stat instead of trying to open /proc/pid/fd/[0-2].
The sudo_ttyname_dev() function maps the given device number to a
string.  On BSD, we can use devname().  On Solaris, _ttyname_dev()
does what we want.  For others we do a breadth-first search of /dev.

--HG--
branch : 1.7