blockjob: Add "ready" field

blockjob: Add "ready" field

When a block job signals readiness, this is currently reported only
through QMP. If qemu wants to use block jobs for internal tasks, there
needs to be another way to correctly detect when a block job may be
completed.

For this reason, introduce a bool "ready" which is set when the block
job may be completed.

Signed-off-by: Max Reitz <[email protected]>
Reviewed-by: Eric Blake <[email protected]>
Reviewed-by: Kevin Wolf <[email protected]>
Message-id: 1414159063[email protected]
Signed-off-by: Stefan Hajnoczi <[email protected]>