fixes #5810: post animateCamera()/easeCamera() callbacks on main thread

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

@@ -380,15 +380,24 @@ public final void easeCamera(CameraUpdate update, int durationMs, boolean easing
             @Override
             public void onCancel() {
                 if (callback != null) {
-                    callback.onCancel();
+                    mMapView.post(new Runnable() {
+                        @Override public void run() {
+                            callback.onCancel();
+                        }
+                    });
                 }
                 invalidateCameraPosition();
             }
 
             @Override
             public void onFinish() {
                 if (callback != null) {
-                    callback.onFinish();
+                    mMapView.post(new Runnable() {
+                        @Override
+                        public void run() {
+                            callback.onFinish();
+                        }
+                    });
                 }
                 invalidateCameraPosition();
             }