net/http: skip a test on netbsd-arm

TestServerDuplicateBackgroundRead has been causing crashes on the
netbsd-arm-bsiegert builder, with the system becoming completely
unresponsive (probably deadlocked). Skip this test while the crash
is under investigation.

Upstream bug report is http://gnats.netbsd.org/53173.

Change-Id: Ib48f19005cf2cbba8a27e75e689c2acb025d8870
Reviewed-on: https://go-review.googlesource.com/106295
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

src/net/http/serve_test.go

@@ -5629,6 +5629,11 @@ func runTimeSensitiveTest(t *testing.T, durations []time.Duration, test func(t *
 // Issue 18535: test that the Server doesn't try to do a background
 // read if it's already done one.
 func TestServerDuplicateBackgroundRead(t *testing.T) {
+	if runtime.GOOS == "netbsd" && runtime.GOARCH == "arm" {
+		// http://gnats.netbsd.org/53173
+		t.Skip("skipping to avoid crash")
+	}
+
 	setParallel(t)
 	defer afterTest(t)