log/syslog: skip unsupported tests on iOS

CL 193843 disabled sysctl on iOS. This change disables two tests that
rely on sysctl.

Updates #34133

Change-Id: I7c569a1992a50ad6027a294c1fd535cccddcfc4e
Reviewed-on: https://go-review.googlesource.com/c/go/+/193844
Run-TryBot: Elias Naur <mail@eliasnaur.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

src/log/syslog/syslog_test.go

@@ -134,6 +134,9 @@ func startServer(n, la string, done chan<- string) (addr string, sock io.Closer,
 }
 
 func TestWithSimulated(t *testing.T) {
+	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
+		t.Skipf("sysctl is not supported on iOS")
+	}
 	t.Parallel()
 	msg := "Test 123"
 	var transport []string
@@ -272,6 +275,9 @@ func check(t *testing.T, in, out string) {
 }
 
 func TestWrite(t *testing.T) {
+	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
+		t.Skipf("sysctl is not supported on iOS")
+	}
 	t.Parallel()
 	tests := []struct {
 		pri Priority