[PATCH v2 0/1] rt_names: add rt_addrprotos with an identifier for keepalived

v2: Add entry to rt_addrprotos rather than rt_addrprotos.d/keepalived.conf

The patch adds an address protocol identifier for keepalived, which now
sets the protocol field when adding IP addresses.

The value of 18 was chosen simply because that is the value of
RTPROT_KEEPALIVED, whick keepalived sets for ip routes and rules. The
value can happily be changed if another value would be better.