qemu: Add monitor functions to set IOThread params

qemu: Add monitor functions to set IOThread params

Add functions to set the IOThreadInfo param data for the live guest.
Modify the _qemuMonitorIOThreadInfo to have a flag to indicate when
a value was set so that we don't set a value unless it was desired
to be set.

Based on code originally posted by Pavel Hrdina <phrdina@redhat.com>,
but extracted into a separate patch. Note that qapi expects to receive
integer parameters rather than unsigned long long or unsigned int's.
QEMU does save the value in larger signed 64 bit values eventually.

Signed-off-by: John Ferlan <jferlan@redhat.com>
ACKed-by: Michal Privoznik <mprivozn@redhat.com>