monitor: Separate QUORUM_REPORT_BAD events according to the node name

monitor: Separate QUORUM_REPORT_BAD events according to the node name

The QUORUM_REPORT_BAD event is emitted whenever there's an I/O error
in a child of a Quorum device. This event is emitted at a maximum rate
of 1 per second. This means that an error in one of the children will
mask errors in the other children if they happen within the same 1
second interval.

This patch modifies qapi_event_throttle_equal() so QUORUM_REPORT_BAD
events are kept separately if they come from different children.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: b989c0cb3755bc4b6696e796fa8ed2ef6c56606a.1457610443.git.berto@igalia.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>