agetty: cleanup debug ifdefs

Signed-off-by: Karel Zak <kzak@redhat.com>
su: fix lastlog and btmp logging

The su(1) logging code mix ups "old" and "new" passwd structs. The
result is things like

	Sep  9 11:50:45 x2 su: (to kzak) kzak on none

in /var/log/messages. The right log entry is

	Sep  9 11:50:45 x2 su: (to root) kzak on pts/3

The bug has been introduced by commit c74a7af17c7a176c358dfaa8e1814786c89ebc14.

References: https://bugzilla.redhat.com/show_bug.cgi?id=1005194
Signed-off-by: Karel Zak <kzak@redhat.com>