qmp: details about CPU definitions in query-cpu-definitions

qmp: details about CPU definitions in query-cpu-definitions

It might be of interest for tooling whether a CPU definition can be safely
used when migrating, or if e.g. CPU features might get lost during
migration when migrationg from/to a different QEMU version or host, even if
the same compatibility machine is used.

Also, we want to know if a CPU definition is static and will never change.
Beause these definitions can then be used independantly of a compatibility
machine and will always have the same feature set, they can e.g. be used
to indicate the "host" model in libvirt later on.

Let's add two return values to query-cpu-definitions, stating for each
returned CPU definition, if it is migration-safe and if it is static.

While "migration-safe" is optional, "static" will be set to "false"
automatically by all implementing architectures. If a model really was
static all the time and will be in the future, this can simply be changed
later.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Message-Id: <20160905085244.99980-2-dahi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>