runtime: skip tests that need fork on darwin/arm

Change-Id: I1bb0b8b11e8c7686b85657050fd7cf926afe4d29
Reviewed-on: https://go-review.googlesource.com/6200
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
diff --git a/src/runtime/crash_test.go b/src/runtime/crash_test.go
index 715b2da..5e26de3 100644
--- a/src/runtime/crash_test.go
+++ b/src/runtime/crash_test.go
@@ -41,6 +41,10 @@
 	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)