migration: Add blocker information

Modify query-migrate so that it has a flag indicating if outbound
migration is blocked, and if it is a list of reasons.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210202135522.127380-2-dgilbert@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
diff --git a/migration/savevm.h b/migration/savevm.h
index aaee252..6461342 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -30,6 +30,7 @@
 #define QEMU_VM_SECTION_FOOTER       0x7e
 
 bool qemu_savevm_state_blocked(Error **errp);
+void qemu_savevm_non_migratable_list(strList **reasons);
 void qemu_savevm_state_setup(QEMUFile *f);
 bool qemu_savevm_state_guest_unplug_pending(void);
 int qemu_savevm_state_resume_prepare(MigrationState *s);