bgpd: Further refine hash lookup to store hash value
Further refine the previous commit to store the hash value in
both the `struct community_list` as well as the `struct rmap_community`
structures. This allows us to know a priori what our hash value
is. This change cuts another couple of seconds of convergence
off to ~55 seconds and further reduces cpu load of bgp:
16 40061.706 433732 92 330102 129
1242965 RWTEX TOTAL
Down from ~43 seconds previously.
Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>