go.net/ipv6: make use of range

R=dave
CC=golang-dev
https://golang.org/cl/10019048
diff --git a/ipv6/icmp_bsd.go b/ipv6/icmp_bsd.go
index 2096079..fd5f83e 100644
--- a/ipv6/icmp_bsd.go
+++ b/ipv6/icmp_bsd.go
@@ -21,7 +21,7 @@
 }
 
 func (f *rawICMPFilter) setAll(block bool) {
-	for i := 0; i < len(f.Filt); i++ {
+	for i := range f.Filt {
 		if block {
 			f.Filt[i] = 0
 		} else {
diff --git a/ipv6/icmp_linux.go b/ipv6/icmp_linux.go
index f60372b..0a70f5f 100644
--- a/ipv6/icmp_linux.go
+++ b/ipv6/icmp_linux.go
@@ -19,7 +19,7 @@
 }
 
 func (f *rawICMPFilter) setAll(block bool) {
-	for i := 0; i < len(f.Data); i++ {
+	for i := range f.Data {
 		if block {
 			f.Data[i] = 1<<32 - 1
 		} else {