qemu: fix concurrency crash bug in force snapshot revert
qemu: fix concurrency crash bug in force snapshot revert

This patch is just revert of [1]. Actually we should NOT pass
QEMU_ASYNC_JOB_NONE as that patch suggests while we are in async job in order
to acquire nested jobs correctly. The patch tries to fix issues introduced by
another patch [2] where jobs are mistakenly cleared out in qemuProcessStop.
Later patch [3] fixed the issue introduced by patch [2]. Now we need to revert
[1] as well as we now still have same concurrency crash issues as [3] described
but for the force revert.

[1] 0c4408c83: qemu: Don't use asyncJob after stop during snapshot revert
[2] 888aa4b6b: qemuDomainObjPrivateDataClear: Don't leak @migParams
[3] d75f865fb: qemu: fix concurrency crash bug in snapshot revert

Signed-off-by: Nikolay Shirokovskiy <7fa0e2698a05be944b362bdf5d7736c0162e16c9@virtuozzo.com>
Reviewed-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>

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