qmp: add new event "command-dropped"

#

##

{ 'command': 'query-sev-capabilities', 'returns': 'SevCapability' }

##

# @CommandDropReason:

#

# Reasons that caused one command to be dropped.

#

# @queue-full: the command queue is full. This can only occur when

#              the client sends a new non-oob command before the

#              response to the previous non-oob command has been

#              received.

#

# Since: 2.12

##

{ 'enum': 'CommandDropReason',

  'data': [ 'queue-full' ] }

##

# @COMMAND_DROPPED:

#

# Emitted when a command is dropped due to some reason.  Commands can

# only be dropped when the oob capability is enabled.

#

# @id: The dropped command's "id" field.

#

# @reason: The reason why the command is dropped.

#

# Since: 2.12

#

# Example:

#

# { "event": "COMMAND_DROPPED",

#   "data": {"result": {"id": "libvirt-102",

#                       "reason": "queue-full" } } }

#

##

{ 'event': 'COMMAND_DROPPED' ,

  'data': { 'id': 'any', 'reason': 'CommandDropReason' } }