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

# gpg: Signature made Wed 12 Oct 2016 09:43:03 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:
  trace: Add missing execution mode of guest events
  trace: introduce a formal group name for trace events
  trace: pass trace-events to tracetool as a positional param
  trace: push reading of events up a level to tracetool main
  trace: rename _read_events to read_events
  trace: get rid of generated-events.h/generated-events.c
  trace: dynamically allocate event IDs at runtime
  trace: dynamically allocate trace_dstate in CPUState
  trace: provide mechanism for registering trace events
  trace: don't abort qemu if ftrace can't be initialized
  trace: emit name <-> ID mapping in simpletrace header
  trace: remove the TraceEventID and TraceEventVCPUID enums
  trace: give each trace event a named TraceEvent struct
  trace: break circular dependency in event-internal.h
  trace: remove duplicate control.h includes in generated-tracers.h
  trace: remove global 'uint16 dstate[]' array
  trace: remove some now unused functions
  trace: convert code to use event iterators
  trace: add trace event iterator APIs
  trace: move colo trace events to net/ sub-directory

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