net: temporary skip hanging test on windows

Update #5971.

R=alex.brainman
CC=golang-dev
https://golang.org/cl/11938046

src/pkg/net/timeout_test.go

@@ -423,6 +423,8 @@ func testVariousDeadlines(t *testing.T, maxProcs int) {
 	switch runtime.GOOS {
 	case "plan9":
 		t.Skipf("skipping test on %q", runtime.GOOS)
+	case "windows":
+		t.Skipf("skipping test on %q, see issue 5971", runtime.GOOS)
 	}
 
 	defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(maxProcs))