argument: Fix missing action_target

Our help output and mainapp code support setting an action_target but
our argument parser doesn't actually interpret the option. This was
mistakenly left out of a previous commit after refactoring.

Change-Id: Ieff5d1a457b9f2b998533b8cefd0251ccb8655f1
Signed-off-by: William A. Kennington III <wak@google.com>
1 file changed