[android] - clear map change listeners when map is destroyed

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/MapView.java

@@ -410,6 +410,7 @@ public class MapView extends FrameLayout implements NativeMapView.ViewCallback {
   @UiThread
   public void onDestroy() {
     destroyed = true;
+    onMapChangedListeners.clear();
     mapCallback.clearOnMapReadyCallbacks();
 
     if (nativeMapView != null && hasSurface) {

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/NativeMapView.java

@@ -100,9 +100,10 @@ final class NativeMapView {
   }
 
   public void destroy() {
-    nativeDestroy();
-    viewCallback = null;
     destroyed = true;
+    onMapChangedListeners.clear();
+    viewCallback = null;
+    nativeDestroy();
   }
 
   public void update() {