Add explicit lint-comment-style fallthrough annotations. GCC now assumes that if you don't have these you're making a mistake, which is annoying. XXX: This changeset updates the AG output files only (by hand) and is XXX: abusive - rebuilding them will erase the change. However, I need XXX: to get things to build before I can try to get AG to issue the XXX: annotations itself, so this seems like a reasonable expedient.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "topic.h"
#include "helpgen.h"

void htmlout(const char *file, struct topic **topics, int ntopics) {
  // XXX
  (void)file;
  (void)topics;
  (void)ntopics;
  fprintf(stderr, "Can't do html output yet\n");
  exit(1);
}