Recognize CARP interfaces when sending packet to a multicast address.
Recognize CARP interfaces when sending packet to a multicast address.

Fix a regression introduced when carp(4) left ether_output() found the
hardway by florian@ and phessler@.

ok benno@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars