Merge tag 'tracing-pull-request' into staging

# gpg: Signature made Mon 08 May 2017 09:39:00 AM EDT
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# 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

* tag 'tracing-pull-request':
  trace: disallow more than 10 arguments per trace event

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>