Fix STUN crash when using IPv6 any address

Ensure that when chan_sip binds to the IPv6 any address ([::]), IPv4
candidates are also added.

(closes issue ASTERISK-21917)
Reported by: Torrey Searle
Patches:
    0023_ipv6_stun_crash.patch uploaded by Torrey Searle (License 5334)


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/11@400681 f38db490-d61c-443f-a65b-d21fe96a405b