avcodec/parser: put lost comments back

Found-by: ubitux
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
configure: use pkg-config to detect libbluray

The current configure fails when static libbluray is compiled with libxml2
support.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
libavcodec/rawdec: avoid memcpy when performing 16-bit samples shift

Signed-off-by: Peter Ross <pross@xvid.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>