agetty: don't put the VC into canonical mode

agetty: don't put the VC into canonical mode

The wait_for_term_input()'s select() needs to be tripped when the user
starts typing. Otherwise the reloads can abort an already in-progress login.

Coupled with \4 and \6 expansions that happen to be there on Fedora Server,
this means reload on every netlink event. With a couple of IPv6 routers
announcing their networks and temporary addresses in use can make it
sometimes virtually impossible to log in.

Seems like zero lflags do the job just fine on a Linux VT. Reset it to
canonical mode before running login.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Stanislav Brabec <sbrabec@suse.cz>
Signed-off-by: Karel Zak <kzak@redhat.com>