qapi: Split machine.json off misc.json

Move commands cpu-add, query-cpus, query-cpus-fast,
query-current-machine, query-hotpluggable-cpus, query-machines,
query-memdev, and set-numa-node with their types from misc.json to new
machine.json.  Also move types X86CPURegister32 and
X86CPUFeatureWordInfo.  Add machine.json to MAINTAINERS section
"Machine core".

Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190619201050.19040-9-armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index bcd9675..f4d8c75 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1268,6 +1268,7 @@
 F: hw/core/null-machine.c
 F: hw/cpu/cluster.c
 F: numa.c
+F: qapi/machine.json
 F: qom/cpu.c
 F: include/hw/boards.h
 F: include/hw/cpu/cluster.h