qemu.tests.qmp_command: Fix and update qmp_cpu

This test previously only checked, if any CPU contains 'current=True'.
With this patch it goes through all cpus and checks, whether the
'current=True' is set only for the last CPU.

Additionally this verification method works with all smp setups.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
qemu.tests.qmp_command: Pylint and Eclipse fixes

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
qemu.tests.qmp_command: Repair function call of has_option()

qemu_command has to be passed to qemu_has_option() function.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
qemu.tests.qmp_command: Add quotes around outputs

Quite often the only difference between HMP and QMP monitor
output is missing or additional space. Add '' around outputs
to help finding those bugs.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>