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)
........

Merged revisions 400681 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 400682 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@400684 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_rtp_asterisk.c

@@ -1661,7 +1661,13 @@ static void rtp_add_candidates_to_ice(struct ast_rtp_instance *instance, struct
 	unsigned int count = PJ_ARRAY_SIZE(address), pos = 0;
 
 	/* Add all the local interface IP addresses */
-	pj_enum_ip_interface(ast_sockaddr_is_ipv4(addr) ? pj_AF_INET() : pj_AF_INET6(), &count, address);
+	if (ast_sockaddr_is_ipv4(addr)) {
+		pj_enum_ip_interface(pj_AF_INET(), &count, address);
+	} else if (ast_sockaddr_is_any(addr)) {
+		pj_enum_ip_interface(pj_AF_UNSPEC(), &count, address);
+	} else {
+		pj_enum_ip_interface(pj_AF_INET6(), &count, address);
+	}
 
 	for (pos = 0; pos < count; pos++) {
 		pj_sockaddr_set_port(&address[pos], port);