Run view nodeapi action on *teaser* in feed generation (quickfix)

Node_feed() instructs the nodeapi view call it invokes to deal with the body of the node, but afterwards it only uses the teaser to generate the feed. So the nodeapi hook should be called with teaser processing in mind. This simple patch fixes that.

Patch is against DRUPAL-4-6 (but it is not possible to categorize this bug as such), and it probably also applies to HEAD.