lib, zebra: extend use of sockunion2ip macro

  * lib/sockunion.c,
  * zebra/zebra_rib.c: replace ->sin.sin_addr.s_addr with sockunion2ip

Signed-off-by: Jorge Boncompte [DTI2] <jorge@dti2.net>
[reworded commit message]
Signed-off-by: David Lamparter <equinox@diac24.net>
2 files changed