libavcodec: Implementation of AC3 fixedpoint decoder

Signed-off-by: Nedeljko Babic <nbabic@mips.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/ac3: rename identifier used to select the fixed point variant

the CONFIG_ prefix is used by configure, using it for other things
is potentially confusing to the reader

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Nedeljko Babic <nbabic@mips.com>
avcodec/ac3dec: avoid #if, use if() instead, its cleaner and shorter

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Nedeljko Babic <nbabic@mips.com>
avcodec/ac3dec_fixed: add missingAVprefix to CODEC_ID

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Nedeljko Babic <nbabic@mips.com>