multichoice_view sometimes doesnt return a value

in the case of user_access('create multichoice') == TRUE and $teaser == TRUE,
mulcithoice_view doesn't return anything, which can break functions later on that expect a return value.

specifically this occurs when a user has the right access, and the multichoice question
is included in an rss feed (like if its promoted to the front page). More detail is
here, but this should take care of it.