Apply a distance adjustment to routes retrieved from IPv4LL/ZeroConf and
DHCP to ensure that Frr (Zebra) can compare other protocol routes, e.g.,
static. Without this Frr will consider all routes read from the kernel
to have a protocol distance of 0, meaning better than static routes that
have a distance of 1.
Initial proposal to fix issue #640
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>