Remove file_set_status() in favor of file_save()

file_set_status() was added in Drupal 6 as a way of changing a temporary file to a permanent file back before file_save() was added. In it's current implementation the function has an annoying overlap with the functionality provided by file_save().

All file_set_status() does is changes the status field of a row in the {files} table and call hook_file_status. But there's nothing to stop you from assigning the file's status and then calling file_save() which would circumvent the call to hook_file_status.

It also diverges from the patterns established else where in core. We don't have a node_set_status() function, you just do a $node->status = 1; node_save($node); and I think the same should be true for files.