qmp: add architecture specific cpu data for query-cpus-fast

qmp: add architecture specific cpu data for query-cpus-fast

The s390 CPU state can be retrieved without interrupting the
VM execution. Extendend the CpuInfoFast union with architecture
specific data and an implementation for s390.

Return data looks like this:
 [
   {"thread-id":64301,"props":{"core-id":0},
    "arch":"s390","cpu-state":"operating",
    "qom-path":"/machine/unattached/device[0]","cpu-index":0},
   {"thread-id":64302,"props":{"core-id":1},
    "arch":"s390","cpu-state":"operating",
    "qom-path":"/machine/unattached/device[1]","cpu-index":1}
]

Signed-off-by: Viktor Mihajlovski <[email protected]>
Reviewed-by: Cornelia Huck <[email protected]>
Reviewed-by: Eric Blake <[email protected]>
Message-Id: <1518797321[email protected]>
Signed-off-by: Cornelia Huck <[email protected]>