Merge remote-tracking branch 'remotes/stefanha/tags/tracing-pull-request' into staging

Tracing pull request

# gpg: Signature made Tue 01 Jul 2014 09:56:27 BST using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"

* remotes/stefanha/tags/tracing-pull-request:
  trace: add qemu_system_powerdown_request and qemu_system_shutdown_request trace events

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --cc vl.c
Simple merge