Add a Global setting for disabling OEM unlocking setting

+ Don't enable OEM unlocking setting if the global setting disallows it.

Bug: 28163088
Change-Id: Ic306da3fa2cecb90865be055566a7e1603e6b5e2

src/com/android/settings/DevelopmentSettings.java

@@ -1014,7 +1014,9 @@ public class DevelopmentSettings extends RestrictedSettingsFragment
             flashLockState = mOemUnlockManager.getFlashLockState();
         }
 
-        return flashLockState != PersistentDataBlockManager.FLASH_LOCK_UNLOCKED;
+        return flashLockState != PersistentDataBlockManager.FLASH_LOCK_UNLOCKED
+                && Settings.Global.getInt(getActivity().getContentResolver(),
+                        Settings.Global.OEM_UNLOCK_DISALLOWED, 0) == 0;
     }
 
     private void updateOemUnlockOptions() {