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

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

Pull request

Fixes for inconsistencies in the trace event format strings, broken
trace_event_get_state() usage, and handle_qmp_command() fix.

# gpg: Signature made Tue 01 Aug 2017 14:16:05 BST
# 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

* remotes/stefanha/tags/tracing-pull-request:
  monitor: Reduce handle_qmp_command() tracing overhead
  trace-events: fix code style: print 0x before hex numbers
  checkpatch: check trace-events code style
  trace-events: fix code style: %# -> 0x%
  coding_style: add point about 0x in trace-events
  trace: add trace_event_get_state_backends()
  trace: add TRACE_<event>_BACKEND_DSTATE()
  trace: ensure unique function / variable names per .stp file
  trace: ensure .stp files are rebuilt if trace tool source changes

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