[Android]fix rtc destroy crash NMS-5434

Author: xgfd3

Android/APIExample/app/src/main/java/io/agora/api/example/examples/advanced/ProcessRawData.java

@@ -137,9 +137,9 @@ public void onDestroy() {
             engine.leaveChannel();
             engine.stopPreview();
         }
-        handler.post(RtcEngine::destroy);
         engine = null;
         super.onDestroy();
+        handler.post(RtcEngine::destroy);
     }
 
     @Override

Android/APIExample/app/src/main/java/io/agora/api/example/examples/advanced/PushExternalVideo.java

@@ -192,9 +192,9 @@ public void onDestroy() {
                 textureBufferHelper = null;
             }
         }
-        handler.post(RtcEngine::destroy);
         engine = null;
         super.onDestroy();
+        handler.post(RtcEngine::destroy);
     }
 
     @Override

Android/APIExample/app/src/main/java/io/agora/api/example/examples/advanced/SwitchCameraScreenShare.java

@@ -182,9 +182,9 @@ public void onDestroy() {
             engine.leaveChannel();
             engine.stopPreview();
         }
-        handler.post(RtcEngine::destroy);
         engine = null;
         super.onDestroy();
+        handler.post(RtcEngine::destroy);
     }