buffer: factor out buffer_adj_size Signed-off-by: Peter Lieven <pl@kamp.de> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Reviewed-by: Daniel P. Berrange <berrange@redhat.com> Message-id: 1446203414-4013-19-git-send-email-kraxel@redhat.com