sm-notify: sm-notify doesn't handle localhost properly

It looks like the existing algorithm for verifying the passed-in bind
address is as broken as statd_matchhostname() used to be: for IP
addresses, AI_CANONNAME is useless.  We need to have getnameinfo(3) or
equivalent in there.

Clean up: extract the logic that verifies the command line bind
address into its own function, and make it handle canonical name
lookup correctly.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>