runtime: don't test gdb on darwin

Fixes #9927

Change-Id: I2114cc21f7a4772e3d42bcad9642a8a545cd8e16
Reviewed-on: https://go-review.googlesource.com/5285
Reviewed-by: Minux Ma <minux@golang.org>
diff --git a/src/runtime/runtime-gdb_test.go b/src/runtime/runtime-gdb_test.go
index a926f5f..36a0dc9 100644
--- a/src/runtime/runtime-gdb_test.go
+++ b/src/runtime/runtime-gdb_test.go
@@ -33,6 +33,10 @@
 `
 
 func TestGdbPython(t *testing.T) {
+	if runtime.GOOS == "darwin" {
+		t.Skip("gdb does not work on darwin")
+	}
+
 	checkGdbPython(t)
 
 	dir, err := ioutil.TempDir("", "go-build")