pcm_bluray: rename pcm-mpeg.c to pcm-bluray.c

The original idea was to collect PCM codecs that could appear in various
MPEG streams in this file. Discussion in IRC lead to the conclusion that
one codec per file would be better and stop the need for #ifdefs.
pcm_bluray: cosmetics
pcm_dvd: consolidate pieces from pcm.c and mpeg.c

Remove the header decoding for PCM audio from mpeg.c and the
20/24bit parts from pcm.c and merge them into a new decoder in
pcm-dvd.c.

The decoder has added support for samples that span multiple
packets and modified 20/24bit group decoding. Both is needed to
decode samples that have been generated with DVD-Lab Pro 2. The
decoding of 16bit PCM and two channel 24bit is identical to
before. No other samples are known to verify the correctness of
the encoding this software does.
The complete list of tested formats is
48kHz/16bit/2-8 channels
48kHz/24bit/2-5 channels
96kHz/16bit/2-4 channels
96kHz/24bit/2 channels

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
vf_lut: Constantize

The pixel format tables are never modified, mark them as constant.

Signed-off-by: Diego Elio Pettenò <flameeyes@flameeyes.eu>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
configure: Add docdir configuration option

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
pcm-dvd: Fix build on big endian

Signed-off-by: Martin Storsjö <martin@martin.st>