http2: skip TestServer_RejectsLargeFrames on windows (fixes build)

Updates golang/go#13434

Change-Id: Icc098d9a6e1af55d36e828fa21d88b967f2f0131
Reviewed-on: https://go-review.googlesource.com/18553Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

http2/server_test.go

@@ -992,6 +992,10 @@ func TestServer_Ping(t *testing.T) {
 }
 
 func TestServer_RejectsLargeFrames(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("see golang.org/issue/13434")
+	}
+
 	st := newServerTester(t, nil)
 	defer st.Close()
 	st.greet()