Merge pull request #4327 from sworleys/Move-Multipath-Num

zebra: Move multipath_num into zrouter

diff --cc zebra/zapi_msg.c
Simple merge

diff --cc zebra/zebra_fpm_netlink.c
Simple merge

diff --cc zebra/zebra_rib.c
Simple merge

diff --cc zebra/zebra_router.h
Simple merge