target-i386: Call cpu_exec_init() on realize

QOM instance_init functions are not supposed to have any side-effects,
as new objects may be created at any moment for querying property
information (see qmp_device_list_properties()).

Calling cpu_exec_init() also affects QEMU's ability to handle errors
during CPU creation, as some actions done by cpu_exec_init() can't be
reverted.

Move cpu_exec_init() call to realize so a simple object_new() won't
trigger it, and so that it is called after some basic validation of CPU
parameters.
Reviewed-by: NIgor Mammedov <imammedo@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

target-i386/cpu.c

@@ -2902,6 +2902,8 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
     }
 
 
+    cpu_exec_init(cs, &error_abort);
+
     if (tcg_enabled()) {
         tcg_x86_init();
     }
@@ -3094,7 +3096,6 @@ static void x86_cpu_initfn(Object *obj)
     FeatureWord w;
 
     cs->env_ptr = env;
-    cpu_exec_init(cs, &error_abort);
 
     object_property_add(obj, "family", "int",
                         x86_cpuid_version_get_family,