New utility gf_compare_addrinfo

Change-Id: I8ea694df480b2cb0f71809d0f696d06b68b5aab3
Improve glusterd_friend_find_by_hostname

glusterd_friend_find_by_hostname will now do an initial quick search for
the peerinfo performing string comparisions on the given host string. It
follows it with a more thorough match, by resolving the addresses and
comparing addrinfos instead of strings.

Change-Id: I092e88bb05f964a23e2f444349e8c4a7a249496b