runtime: skip tests that need fork on darwin/arm

Change-Id: I1bb0b8b11e8c7686b85657050fd7cf926afe4d29
Reviewed-on: https://go-review.googlesource.com/6200Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

src/runtime/crash_cgo_test.go

@@ -57,6 +57,7 @@ func TestCgoExternalThreadSIGPROF(t *testing.T) {
 	case "plan9", "windows":
 		t.Skipf("no pthreads on %s", runtime.GOOS)
 	case "darwin":
+		if runtime.GOARCH != "arm" {
 			// static constructor needs external linking, but we don't support
 			// external linking on OS X 10.6.
 			out, err := exec.Command("uname", "-r").Output()
@@ -68,6 +69,7 @@ func TestCgoExternalThreadSIGPROF(t *testing.T) {
 				t.Skipf("no external linking on OS X 10.6")
 			}
 		}
+	}
 	if runtime.GOARCH == "ppc64" || runtime.GOARCH == "ppc64le" {
 		// TODO(austin) External linking not implemented on
 		// ppc64 (issue #8912)

src/runtime/crash_test.go

@@ -41,6 +41,10 @@ func executeTest(t *testing.T, templ string, data interface{}, extra ...string)
 	switch runtime.GOOS {
 	case "android", "nacl":
 		t.Skipf("skipping on %s", runtime.GOOS)
+	case "darwin":
+		if runtime.GOARCH == "arm" {
+			t.Skipf("skipping on %s/%s", runtime.GOOS, runtime.GOARCH)
+		}
 	}
 
 	checkStaleRuntime(t)