Replace nearly all XXX0vv comments with smarter ones

So, back long ago, XXX012 meant, "before Tor 0.1.2 is released, we
had better revisit this comment and fix it!"

But we have a huge pile of such comments accumulated for a large
number of released versions!  Not cool.

So, here's what I tried to do:

  * 0.2.9 and 0.2.8 are retained, since those are not yet released.

  * XXX+ or XXX++ or XXX++++ or whatever means, "This one looks
    quite important!"

  * The others, after one-by-one examination, are downgraded to
    plain old XXX.  Which doesn't mean they aren't a problem -- just
    that they cannot possibly be a release-blocking problem.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/or/buffers.c b/src/or/buffers.c
index cdc71ab9db..8b9a53c699 100644
--- a/src/or/buffers.c
+++ b/src/or/buffers.c
@@ -509,12 +509,12 @@ read_to_chunk_tls(buf_t *buf, chunk_t *chunk, tor_tls_t *tls,
  * (because of EOF), set *<b>reached_eof</b> to 1 and return 0. Return -1 on
  * error; else return the number of bytes read.
  */
-/* XXXX024 indicate "read blocked" somehow? */
+/* XXXX indicate "read blocked" somehow? */
 int
 read_to_buf(tor_socket_t s, size_t at_most, buf_t *buf, int *reached_eof,
             int *socket_error)
 {
-  /* XXXX024 It's stupid to overload the return values for these functions:
+  /* XXXX It's stupid to overload the return values for these functions:
    * "error status" and "number of bytes read" are not mutually exclusive.
    */
   int r = 0;
@@ -687,7 +687,7 @@ flush_chunk_tls(tor_tls_t *tls, buf_t *buf, chunk_t *chunk,
 int
 flush_buf(tor_socket_t s, buf_t *buf, size_t sz, size_t *buf_flushlen)
 {
-  /* XXXX024 It's stupid to overload the return values for these functions:
+  /* XXXX It's stupid to overload the return values for these functions:
    * "error status" and "number of bytes flushed" are not mutually exclusive.
    */
   int r;