Fixed a memory leak in dvbsubenc.c: sub->num_rects was reduced without freeing the associated rects.

Signed-off-by: Wim Vander Schelden <lists@fixnum.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/dvbsubdec: Remove unused display_list_size

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>