resist calling wierdly entered ip4 addresses ip6.

Notes:
Sat Oct 21 22:39:31 EDT 2006 geoff
    parseip should be changed to return -1 if it failed to
    parse, and 0 otherwise, and not let callers care.


Reference: /n/sources/patch/sorry/libip-v4
Date: Fri Oct 20 16:23:38 CES 2006
Signed-off-by: quanstro@quanstro.net
Reviewed-by: geoff

--- /sys/src/libip/parseip.c	Fri Oct 20 16:22:56 2006
+++ /sys/src/libip/parseip.c	Fri Oct 20 16:22:54 2006
@@ -67,7 +67,7 @@
 		memmove(&to[elipsis+16-i], &to[elipsis], i-elipsis);
 		memset(&to[elipsis], 0, 16-i);
 	}
-	if(v4){
+	if(v4 || memcmp(to, v4prefix, IPv4off) == 0){
 		to[10] = to[11] = 0xff;
 		return nhgetl(to+12);
 	} else