veyron/tools/mgmt/device/devicex: undo go/vcl/5860 for MacOS to fix integr. test

using stat -c seems to break the integration test on macos
(https://github.com/veyron/release-issues/issues/1198) so keep using ls for
darwin for now.

Change-Id: I9feb6125de9663eb5f36d2f3b5d4c56b5fd4fb02
diff --git a/tools/mgmt/device/devicex b/tools/mgmt/device/devicex
index bff6f43..c855d9d 100755
--- a/tools/mgmt/device/devicex
+++ b/tools/mgmt/device/devicex
@@ -243,7 +243,14 @@
 #  user owning the device manager
 ###############################################################################
 getdevowner() {
-  stat -c "%U" "${VANADIUM_DEVICE_DIR}"
+  case "$(uname)" in
+    "Darwin")
+      ls -dl  "${VANADIUM_DEVICE_DIR}" | awk '{print $3}'
+      ;;
+    "Linux")
+      stat -c "%U" "${VANADIUM_DEVICE_DIR}"
+      ;;
+  esac
 }
 
 ###############################################################################