Fix possible memory leak for Android

/godot_dev/platform/android/java/src/com/google/android/vending/expansion/downloader/impl/DownloaderService.java:575: Error: The WIFI_SERVICE must be looked up on the Application context or memory will leak on devices < Android N. Try changing  to .getApplicationContext()  [WifiManagerLeak]
            mWifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
                                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

   Explanation for issues of type "WifiManagerLeak":
   On versions prior to Android N (24), initializing the WifiManager via
   Context#getSystemService can cause a memory leak if the context is not the
   application context. Change context.getSystemService(...) to
   context.getApplicationContext().getSystemService(...).

1 errors, 0 warnings

platform/android/java/src/com/google/android/vending/expansion/downloader/impl/DownloaderService.java

@@ -569,10 +569,10 @@ public abstract class DownloaderService extends CustomIntentService implements I
      */
     void pollNetworkState() {
         if (null == mConnectivityManager) {
-            mConnectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
+            mConnectivityManager = (ConnectivityManager) getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
         }
         if (null == mWifiManager) {
-            mWifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
+            mWifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
         }
         if (mConnectivityManager == null) {
             Log.w(Constants.TAG,