[Lucid CVE-2013-0871] race conditon in ptrace

[Luis Henriques]

>From the description:

 "A race conditon in ptrace can lead to kernel stack corruption and
  arbitrary kernel-mode code execution."

Following this email, there are 4 patches that fix this issue for Lucid.
It contains a extra patch (the other series had only 3) as I was
triggering a different issue:

I was hitting the WARN_ON() in the wake_up_process(), that is added by
patch 4 in this serie ("wake_up_process() should be never used to wakeup a
TASK_STOPPED/TRACED task").

Again, I did a lot of testing with this backport and although I'm pretty
confident that I'm not introducing any regressions, a good review would be
great!