Add several test scripts wrapping test_workqueue

This is a fairly easy way for us to get our test coverage up on
compat_threads.c and workqueue.c -- I already implemented these
tests, so we might as well enable them.

src/test/test_workqueue.c

@@ -400,6 +400,9 @@ main(int argc, char **argv)
   }
 
   rq = replyqueue_new(as_flags);
+  if (as_flags && rq == NULL)
+    return 77; // 77 means "skipped".
+
   tor_assert(rq);
   tp = threadpool_new(opt_n_threads,
                       rq, new_state, free_state, NULL);