Respond to comment deletion.
This hook is invoked from comment_delete_multiple() after field_attach_delete() has called and after the comment has been removed from the database.
Drupal\comment\Comment $comment: The comment object for the comment that has been deleted.
Note: this list is generated by pattern matching, so it may include some functions that are not actually implementations of this hook.
function hook_comment_delete(Drupal\comment\Comment $comment) {
drupal_set_message(t('Comment: @subject has been deleted', array(
'@subject' => $comment->subject,
)));
}