Honour tty field in /etc/inittab

The problem was caused by procd not opening /dev/tty* (whichever was
specified for the ID field /etc/inittab), causing /proc/PID/fd to
point to /dev/console instead.

This is a rework of e63051d9, which did not initialise the console
pointer and did not check the tty pointer in askconsole. askfirst
was not completely fixed as it expected the console parameter on
the commandline, which is no longer necessary because procd opens
the console prior to fork()-ing.

Signed-off-by: Michel Stam <m.stam@fugro.nl>