[libvirt] [RFC] make virDomainQemuMonitorCommand work in any libvirt state

Hi, all. We would like to use virDomainQemuMonitorCommand to query qemu independently of libvirt state. Currenly it is not possible. This API call takes job condition just like any other call and thus is unavailable on any lengthy(or stucked) synchronous job. I've already posted this question in list, just failed to find the reference. Somebody suggested to use proxy (and even an implementation) in between qemu and libvirt that can inject commands to qemu and filter replies. It is not really convinient. This way test setups will be different from production and we can not investigate problems in production environment. I'd like to drop acquiring job condition in the call as this function does not deal with libvirt state (except for the taint but is is ok, we will not mess things up here). But this is not enough, we need to make qemu monitor deal with many qemu commands simultaneously. Looks like it is quite a big change for test/debug case. But I guess eventually normal user cases can get benefits too from this monitor changes. For example all query API calls that query qemu directly can be changed to not to wait for some synchronous job finishing.(qemuDomainGetBlockJobInfo for example). Nikolay