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

# gpg: Signature made Mon 19 Feb 2018 16:19:46 GMT
# gpg:                using RSA key 9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/tracing-pull-request:
  trace: avoid SystemTap "char const" warnings
  tracetool: For ust trace bool type as ctf_integer
  tracetool: Update argument format regex to non-greedy star

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