libopenjpeg can return images with components without data.

This fixes segmentation faults.
Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
(cherry picked from commit 3ef57029)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>