Fix valid_ipv4addr().

Fix first byte check.

alterator-net-functions/alterator-net-functions

@@ -46,7 +46,8 @@ valid_ipv4addr()
 		i=$(($i+1))
 	done
 
-	[ $i -eq 2 ] 2>/dev/null ||
+	[ $i -eq 2  -a \
+		"$byte" -gt 0 -a "$byte" -lt 255 ] 2>/dev/null ||
 		return 1
 }