Use the compat name space for your menu items like this:
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:compat="http://schemas.android.com/apk/res-auto" >
<item android:id="@+id/action_whatever"
android:icon="@drawable/ic_action_whatever"
android:title="@string/whatever"
compat:showAsAction="ifRoom" />
</menu>