fix utf-16 reading and make it work on android

src/app_events.cpp

@@ -98,7 +98,7 @@ void App::pick_file(std::vector<std::string> types, std::function<void (std::str
             callback(path);
     });
 #elif __ANDROID__
-    //android_pick_file(and_app, callback);
+    android_pick_file(and_app, callback);
 #elif _WIN32
     std::string filter = "Supported Files (";
     bool first_type = true;