don't forget about ipv6 when doing reverse queries.  at least don't
screw up strings like
	0.3.0.0.2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.e.3.a.b.3.0.5.0.1.0.0.2.ip6.arpa

Reference: /n/sources/patch/applied/dnsquery-ip6
Date: Fri May  4 04:26:18 CES 2012
Signed-off-by: quanstro@quanstro.net

--- /sys/src/libndb/dnsquery.c	Fri May  4 04:25:22 2012
+++ /sys/src/libndb/dnsquery.c	Fri May  4 04:25:21 2012
@@ -81,7 +81,8 @@
 	char *p, *np;
 	int len;
 
-	if(strstr(ip, "in-addr.arpa") || strstr(ip, "IN-ADDR.ARPA")){
+	if(strstr(ip, "in-addr.arpa") || strstr(ip, "IN-ADDR.ARPA")
+	|| strstr(ip, "ip6.arpa") || strstr(ip, "IP6.ARPA")){
 		nstrcpy(rip, ip, rlen);
 		return;
 	}