qmp: add set-numa-node command

Command is allowed to run only in preconfig stage and
will allow to configure numa mapping for CPUs depending
on possible CPUs layout (query-hotpluggable-cpus) for
given machine instance.

Example of configuration session:
$QEMU -smp 2 --preconfig ...

QMP:
-> {'execute': 'query-hotpluggable-cpus' }
<- {'return': [
       {'props': {'core-id': 0, 'thread-id': 0, 'socket-id': 1}, ... },
       {'props': {'core-id': 0, 'thread-id': 0, 'socket-id': 0}, ... }
   ]}

-> {'execute': 'set-numa-node', 'arguments': { 'type': 'node', 'nodeid': 0 } }
<- {'return': {}}
-> {'execute': 'set-numa-node', 'arguments': { 'type': 'cpu',
       'node-id': 0, 'core-id': 0, 'thread-id': 0, 'socket-id': 1, }
   }
<- {'return': {}}

-> {'execute': 'set-numa-node', 'arguments': { 'type': 'node', 'nodeid': 1 } }
-> {'execute': 'set-numa-node', 'arguments': { 'type': 'cpu',
       'node-id': 1, 'core-id': 0, 'thread-id': 0, 'socket-id': 0 }
   }
<- {'return': {}}

-> {'execute': 'query-hotpluggable-cpus' }
<- {'return': [
       {'props': {'core-id': 0, 'thread-id': 0, 'node-id': 0, 'socket-id': 1}, ... },
       {'props': {'core-id': 0, 'thread-id': 0, 'node-id': 1, 'socket-id': 0}, ... }
   ]}

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1525423069-61903-11-git-send-email-imammedo@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
[ehabkost: Changed "since 2.13" to "since 3.0"]
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>