package/xbmc: add missing dependency on libtheora

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Cc: Bernd Kuhls <berndkuhls@hotmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>