internalip: Output broken by update to iproute2

[stoneycode]

Observed in iproute2-ss180813: output is '1000'
This corresponds to the new output of ip route get n.n.n.n, that adds now default uid 1000 at the end.
Last line of code
ip route get $t | awk '{print $NF; exit}'
should now hardcode field 7
ip route get $t | awk '{print $7; exit}'