when using field-perm, cck fails to save select/multi-select fields because of failure to follow the drupal core node_save idiom

in drupal core node_save, when saving a node to the DB, the first thing that is done is to check for any fields that weren't posted (as a result of other module interference via form_alter), and replace any of those fields with whatever value was in the previous revision of the node

this pattern is not followed by cck because during node_save() -> node_submit() -> content_submit() -> _content_widget_invoke('process form values'), cck detects any fields that were missing in the node objects and fills those gaps in with widget-specific default starting data

the result of this, is that when using cck_field_perms or any other similar module, if you are currently in a node edit form as a user that is unable to see any select or multi-select fields, then your form submission will blow out those fields that you are unable to see.

the attached patch fixes this issue without breaking _content_widget_invoke in its many other uses