act on entity bundle delete to clean up {flag_types} table

There's actually a bug here too:

function flag_node_type_delete($info) {
  // Remove entry from flaggable content types.
  db_delete('flag_types')->condition('type', $info->type)->execute();
}

This will remove types from flags for entities other than the current one if they happen to match.

Eg, both node and product entities have a bundle 'foo'. Both have flags. Deleting the product foo bundle will also zap the node flag's applicability to the node foo bundle.

Committed this patch.

Tested it with deleting a node type 'foo' when there's also a vocabulary 'foo' and vice versa. Will also remove the comment type from comment flags, as hook_field_attach_delete_bundle() is also invoked for comments when a node type is deleted.