xorriso: disable libcdio

xorriso: disable libcdio

xorriso and libcdio define identically named symbols. This breaks static
linking.

Besides, upstream suggested that on Linux the built-in libburn adapter is much
better tested than libcdio.

Disable libcdio.

Fixes:
http://autobuild.buildroot.net/results/430/430a6b548fcc311f20ea71cecaa11fafac1d5a19/
http://autobuild.buildroot.net/results/a5d/a5d0f8bec0d39e48f6dfe4ecc07fe0ca3c6bd70a/

Cc: Steve Kenton <skenton@ou.edu>
Suggested-by: Thomas Schmitt <scdbackup@gmx.net>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Steve Kenton <skenton@ou.edu>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>