qapi: Factor out QAPISchemaObjectType.check_clash() Consolidate two common sequences of clash detection into a new QAPISchemaObjectType.check_clash() helper method. No change to generated code. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <1447836791-369-13-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>