bluray: fix abort() when empty overlay is closed

HDMV titles can construct empty overlay with invisible buttons to enable navigation.
This is used in ex. photo galleries (to flip image) and with audio navigation ("spoken menu").

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
bluray: use bd_get_main_title()

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
bluray: enable pop-up menu

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
bluray: fix setting parent input

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
Bump DVBsub priority above avcodec

Since now avcodec module accepts dvbsub, it is always taken, even if it
fails to decode...

Close #10655