Merge remote-tracking branch 'remotes/qmp-unstable/queue/qmp' into staging

Merge remote-tracking branch 'remotes/qmp-unstable/queue/qmp' into staging

* remotes/qmp-unstable/queue/qmp:
  monitor: fix qmp_getfd() fd leak in error case
  HMP: support specifying dump format for dump-guest-memory
  HMP: fix doc of dump-guest-memory
  qmp: object-add: Validate class before creating object
  monitor: Add device_add and device_del completion.
  monitor: Add command_completion callback to mon_cmd_t.
  monitor: Fix drive_del id argument type completion.
  error: Remove some unused headers
  qerror.h: Replace QERR_NOT_SUPPORTED with QERR_UNSUPPORTED
  qerror.h: Remove QERR defines that are only used once
  qerror.h: Remove unused error classes
  error: Print error_report() to stderr if using qmp
  monitor: Remove unused monitor_print_filename
  error: Privatize error_print_loc
  vnc: Remove default_mon usage
  slirp: Remove default_mon usage

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