OptionalPermissions: fix call to buildPermissionRequestIntent

There's no need to call getApplication().

Change-Id: I56e8a6a4ab230275c70e240e53a893e05400f2f9

samples/OptionalPermissions/src/com/example/android/permdemo/PrefsFragment.java

@@ -258,8 +258,8 @@ public class PrefsFragment extends PreferenceFragment {
     }
 
     private void onPromptPermissionsClicked(String... permissions) {
-        Intent i = getActivity().getApplication()
-                .getPackageManager().buildPermissionRequestIntent(permissions);
+        Intent i = getActivity().getPackageManager()
+                .buildPermissionRequestIntent(permissions);
         startActivityForResult(i, REQUEST_CODE_PROMPT_PERMISSIONS);
     }