IPv6 ping only blindly marks host Down

[dschultzca]

In all repo branch versions of ping.c code, IPv6 hosts as marked down in the } else if (host->availability_method == AVAIL_PING) { block.

		if (!strstr(host->hostname, "localhost")) {
			if (get_address_type(host) == 1) {
				if (host->ping_method == PING_ICMP) {
					ping_result = ping_icmp(host, ping);
				} else if (host->ping_method == PING_UDP) {
					ping_result = ping_udp(host, ping);
				} else if (host->ping_method == PING_TCP) {
					ping_result = ping_tcp(host, ping);
				}
			} else if (host->availability_method == AVAIL_PING) {
				snprintf(ping->ping_status, 50, "0.000");
				snprintf(ping->ping_response, SMALL_BUFSIZE, "PING: Device is Unknown or is IPV6.  Please use the SNMP ping options only.");
				return HOST_DOWN;
			}

It is expected that IPv6 hosts are treated as well as IPv4 hosts and provide a true ping result on both Linux and Windows OS.

[TheWitness]

Duplicate of #127. I'm closing this one. I think until we get a contribution of PING6, we will have to close this one.