jpeg2000: artefacts with losless 16bpp

[ami_stuff]

C:\>ffmpeg -i lossless_16bpp.jp2 out.bmp
ffmpeg version N-73036-g631d56f Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.5.0 (GCC) 20100414 (Fedora MinGW 4.5.0-1.fc14)
  configuration: --prefix=/var/www/users/research/ffmpeg/snapshots/build --arch=
x86 --target-os=mingw32 --cross-prefix=i686-pc-mingw32- --cc='ccache i686-pc-min
gw32-gcc' --enable-pthreads --enable-memalign-hack --enable-runtime-cpudetect --
enable-cross-compile --enable-static --disable-shared --extra-libs='-lws2_32 -lw
inmm -lpthread' --extra-cflags='--static -I/var/www/users/research/ffmpeg/snapsh
ots/build/include' --extra-ldflags='-static -L/var/www/users/research/ffmpeg/sna
pshots/build/lib' --enable-bzlib --enable-zlib --enable-gpl --enable-version3 --
enable-nonfree --enable-libx264 --enable-libspeex --enable-libtheora --enable-li
bvorbis --enable-libfaac --enable-libxvid --enable-libopencore-amrnb --enable-li
bopencore-amrwb --enable-libmp3lame --enable-libfreetype --enable-libvpx --disab
le-decoder=libvpx
  libavutil      54. 27.100 / 54. 27.100
  libavcodec     56. 42.100 / 56. 42.100
  libavformat    56. 37.100 / 56. 37.100
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 17.100 /  5. 17.100
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.100 /  1.  2.100
  libpostproc    53.  3.100 / 53.  3.100
[jpeg2000 @ 0x298f8e0] Progression order RPCL
Input #0, j2k_pipe, from 'lossless_16bpp.jp2':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: jpeg2000 (JPEG 2000 codestream restriction 0), gray16le,
 999x749, 25 tbr, 25 tbn, 25 tbc
Output #0, image2, to 'out.bmp':
  Metadata:
    encoder         : Lavf56.37.100
    Stream #0:0: Video: bmp, gray, 999x749, q=2-31, 200 kb/s, 25 fps, 25 tbn, 25
 tbc
    Metadata:
      encoder         : Lavc56.42.100 bmp
Stream mapping:
  Stream #0:0 -> #0:0 (jpeg2000 (native) -> bmp (native))
Press [q] to stop, [?] for help
[jpeg2000 @ 0x25dfc20] Progression order RPCL
frame=    1 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A
video:732kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing o
verhead: unknown

[Michael Niedermayer]

Fixed in 8ff09e90986941942f4dc9eb3dc11073215589a3