Add AUV2 FourCC

[ami_stuff]

This seems to be rawvideo/PIX_FMT_UYVY422 format.

​http://samples.multimedia.cx/V-codecs/auv2.avi

libavcodec/raw.c:
+ { PIX_FMT_UYVY422, MKTAG('A', 'U', 'V', '2') },

libavformat/riff.c:
+ { CODEC_ID_RAWVIDEO,     MKTAG('A', 'U', 'V', '2') },

C:\>ffmpeg -i C:\auv2.avi
FFmpeg version git-N-29181-ga304071, Copyright (c) 2000-2011 the FFmpeg develope
rs
  built on Apr 18 2011 21:24:03 with gcc 4.5.2
  configuration: --enable-gpl --enable-version3 --enable-runtime-cpudetect --ena
ble-memalign-hack --enable-avisynth --enable-bzlib --enable-frei0r --enable-libo
pencore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --
enable-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-libschroedinger
 --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libvpx --enabl
e-libx264 --enable-libxavs --enable-libxvid --enable-zlib --cross-prefix=i686-w6
4-mingw32- --target-os=mingw32 --arch=x86_32 --extra-cflags=-I/home/kyle/softwar
e/ffmpeg/external-libraries/win32/include --extra-ldflags=-L/home/kyle/software/
ffmpeg/external-libraries/win32/lib --pkg-config=pkg-config
  libavutil    50. 40. 1 / 50. 40. 1
  libavcodec   52.120. 0 / 52.120. 0
  libavformat  52.108. 0 / 52.108. 0
  libavdevice  52.  4. 0 / 52.  4. 0
  libavfilter   1. 79. 0 /  1. 79. 0
  libswscale    0. 13. 0 /  0. 13. 0
[avi @ 01CEC000] non-interleaved AVI
[avi @ 01CEC000] Could not find codec parameters (Video: auv2 / 0x32767561, 320x
240)
Input #0, avi, from 'C:\auv2.avi':
  Duration: 00:00:00.59, start: 0.000000, bitrate: 27915 kb/s
    Stream #0.0: Video: auv2 / 0x32767561, 320x240, 15 fps, 15 tbr, 15 tbn, 15 t
bc
    Stream #0.1: Audio: pcm_u8, 22050 Hz, 1 channels, u8, 176 kb/s
At least one output file must be specified

[Carl Eugen Hoyos]

Applied in 3e1c59ebc642831395bb5bcdc763520722679a6c, thank you.