vl: Split off user_creatable_print_help()

Printing help for --object is something that we not only want in the
system emulator, but also in tools that support --object. Move it into a
separate function in qom/object_interfaces.c to make the code accessible
for tools.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/include/qom/object_interfaces.h b/include/qom/object_interfaces.h
index 682ba1d..3e4e1d9 100644
--- a/include/qom/object_interfaces.h
+++ b/include/qom/object_interfaces.h
@@ -133,6 +133,18 @@
                                     QemuOpts *opts, Error **errp);
 
 /**
+ * user_creatable_print_help:
+ * @type: the QOM type to be added
+ * @opts: options to create
+ *
+ * Prints help if requested in @opts.
+ *
+ * Returns: true if @opts contained a help option and help was printed, false
+ * if no help option was found.
+ */
+bool user_creatable_print_help(const char *type, QemuOpts *opts);
+
+/**
  * user_creatable_del:
  * @id: the unique ID for the object
  * @errp: if an error occurs, a pointer to an area to store the error