ipv6: remove unnecessary double quotations from test messages

Change-Id: I1d91ddf7fb4eebd4782f0621446ec2820d132788
Reviewed-on: https://go-review.googlesource.com/3562
Reviewed-by: Ian Lance Taylor <iant@golang.org>
diff --git a/ipv6/multicastsockopt_test.go b/ipv6/multicastsockopt_test.go
index bf59750..fe0e6e1 100644
--- a/ipv6/multicastsockopt_test.go
+++ b/ipv6/multicastsockopt_test.go
@@ -27,14 +27,14 @@
 func TestPacketConnMulticastSocketOptions(t *testing.T) {
 	switch runtime.GOOS {
 	case "nacl", "plan9", "solaris", "windows":
-		t.Skipf("not supported on %q", runtime.GOOS)
+		t.Skipf("not supported on %s", runtime.GOOS)
 	}
 	if !supportsIPv6 {
 		t.Skip("ipv6 is not supported")
 	}
 	ifi := nettest.RoutedInterface("ip6", net.FlagUp|net.FlagMulticast|net.FlagLoopback)
 	if ifi == nil {
-		t.Skipf("not available on %q", runtime.GOOS)
+		t.Skipf("not available on %s", runtime.GOOS)
 	}
 
 	m, ok := nettest.SupportsRawIPSocket()
@@ -120,7 +120,7 @@
 		switch runtime.GOOS {
 		case "freebsd", "linux":
 		default: // platforms that don't support MLDv2 fail here
-			t.Logf("not supported on %q", runtime.GOOS)
+			t.Logf("not supported on %s", runtime.GOOS)
 			return
 		}
 		t.Error(err)