trace: [qmp] Add commands to query and control event tracing state

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Message-id: 20140825111957.31112.31733.stgit@fimbulvetr.bsc.es
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
trace: [hmp] Reimplement "trace-event" and "info trace-events" using QMP

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Message-id: 20140825112002.31112.60143.stgit@fimbulvetr.bsc.es
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
trace-events: drop orphan virtio_blk_data_plane_complete_request

This trace event has not been in use since commit
b002254dbd4c19a01f29790f840f983803e26893 ("virtio-blk: Unify
{non-,}dataplane's request handlings").

Cc: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-id: 1411394595-15300-2-git-send-email-stefanha@redhat.com
trace-events: drop orphan usb_mtp_data_out

This trace event was added in commit
840a178c94dbd3f5b5550fb8621620cb761de72d ("usb: mtp filesharing") but
never used.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-id: 1411394595-15300-3-git-send-email-stefanha@redhat.com
trace-events: drop orphan iscsi trace events

iscsi_aio_write16_cb, iscsi_aio_writev, iscsi_aio_read16_cb, and
iscsi_aio_readv have not not been in use since commit
063c3378a9e3c25cc0afac3c72e4823d0621e352 ("block/iscsi: introduce
bdrv_co_{readv, writev, flush_to_disk}").

These were the only trace events in block/iscsi.c so drop the the
trace.h include.

Cc: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-id: 1411394595-15300-4-git-send-email-stefanha@redhat.com