dropbear: Make utmp and putuline support configurable via seperate config options

Utmp support tracks who is currenlty logged in by logging info to the file /var/run/utmp (supported by busybox)
Putuline support will use the utmp structure to write to the utmp file

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@49333 3c298f89-4303-0410-b956-a3cf2f4a3e73