python/qemu/qmp.py: QMP debug with VM label

python/qemu/qmp.py: QMP debug with VM label

QEMUMachine writes some messages to the default logger.
But it sometimes hard to read the output if we have requests to
more than one VM.
This patch adds a label to the logger in the debug mode.

Signed-off-by: Oksana Vohchana <[email protected]>
Reviewed-by: John Snow <[email protected]>
Reviewed-by: Wainer dos Santos Moschetta <[email protected]>
Reviewed-by: Cleber Rosa <[email protected]>
Message-Id: <20200316103203[email protected]>
Signed-off-by: Cleber Rosa <[email protected]>