Fix for crash during monkey testing.

adb -e shell monkey -p my.package -v 10000

java.lang.NullPointerException
at com.actionbarsherlock.internal.ActionBarSherlockNative.dispatchOptionsItemSelected(ActionBarSherlockNative.java:78)
at com.actionbarsherlock.app.SherlockPreferenceActivity.onOptionsItemSelected(SherlockPreferenceActivity.java:148)
at android.app.Activity.onMenuItemSelected(Activity.java:2534)
at com.android.internal.widget.ActionBarView$3.onClick(ActionBarView.java:167)