[RCF 0/6 V2] A general notification in GDB RSP

[Yao Qi]

Hi,
This is the V2 of this patch series, and V2 is here,

  [RCF 0/4] A general notification in GDB RSP
  http://sourceware.org/ml/gdb-patches/2012-08/msg00703.html

Compared with V1, here are some changes,

  - queue.h is revised after several Doug's reviews.
  - support both non-stop and all-stop mode.  V1 only works on
    non-stop mode, as original notification design is for non-stop.
    V2 supports all-stop mode.

This series depends on this patch,

  [RFC 0/2, gdbserver] Set linux target in async mode in default
  http://sourceware.org/ml/gdb-patches/2012-09/msg00349.html

The whole stuff can be found in this git branch.

  https://github.com/qiyao/gdb/tree/async-general-notif-v2

The whole stuff is tested on x86_64 linux with {native, gdbserver,
extended-gdbserver} x {sync, async}.  No regression.

Patch 2/6 and 3/6 are somewhat mechanical that switching code to use
QUEUE stuff.  Patch 5/6 is to support notification in all-stop mode.
Patch 6/6 is almost same as it is in V1.