adpcm_sbpro_3: fix memory eating

[ami_stuff]

 http://samples.mplayerhq.hu/A-codecs/musepack/01%20-%20Pumpkin%20and%20Honey%20Bunny%20(dialogue)%20-%20Dick%20Dale%20&%20His%20Del-Tones%20,%20Misirlou.mpc

C:\ffmpeg -acodec adpcm_sbpro_3 -i "01 - Pumpkin and Honey Bunny (dialogue) - Dick Dale & His Del-Tones , Misirlou.mpc" -f null -
ffmpeg version N-46755-ge70144c Copyright (c) 2000-2012 the FFmpeg developers
  built on Nov 15 2012 02:38:20 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-w32threads --enable-memalign-hack --enable-runtime-cpudetect
--enable-cross-compile --enable-static --disable-shared --extra-libs='-lws2_32 -
lwinmm -lpthread' --extra-cflags='--static -I/var/www/users/research/ffmpeg/snap
shots/build/include' --extra-ldflags='-static -L/var/www/users/research/ffmpeg/s
napshots/build/lib' --enable-bzlib --enable-zlib --enable-gpl --enable-version3
--enable-nonfree --enable-libx264 --enable-libspeex --enable-libtheora --enable-
libvorbis --enable-libfaac --enable-libxvid --enable-libopencore-amrnb --enable-
libopencore-amrwb --enable-libmp3lame --enable-libvpx --disable-decoder=libvpx
  libavutil      52.  6.100 / 52.  6.100
  libavcodec     54. 71.100 / 54. 71.100
  libavformat    54. 36.100 / 54. 36.100
  libavdevice    54.  3.100 / 54.  3.100
  libavfilter     3. 23.100 /  3. 23.100
  libswscale      2.  1.102 /  2.  1.102
  libswresample   0. 16.100 /  0. 16.100
  libpostproc    52.  1.100 / 52.  1.100
Input #0, mpc, from '01 - Pumpkin and Honey Bunny (dialogue) - Dick D
ale & His Del-Tones , Misirlou.mpc':
  Metadata:
    Track           : 1
    Year            : 1994
    Genre           : Soundtrack
    Artist          : Soundtrack
    Album           : Pulp Fiction
    Title           : Dick Dale & His Del-Tones / Misirlou
    Comment         : EAC secure - ripped by juans for www.enkeywebsite.net
  Duration: 00:02:30.18, start: 0.000000, bitrate: 129 kb/s
    Stream #0:0: Audio: adpcm_sbpro_3, 44100 Hz, stereo, s16, 264 kb/s
Output #0, null, to 'pipe:':
  Metadata:
    Track           : 1
    Year            : 1994
    Genre           : Soundtrack
    Artist          : Soundtrack
    Album           : Pulp Fiction
    Title           : Dick Dale & His Del-Tones / Misirlou
    Comment         : EAC secure - ripped by juans for www.enkeywebsite.net
    encoder         : Lavf54.36.100
    Stream #0:0: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (adpcm_sbpro_3 -> pcm_s16le)
Press [q] to stop, [?] for help
Multiple frames in a packet from stream 0
[output stream 0:0 @ 0x1fb74e0] 100 buffers queued in output stream 0:0, somethi
ng may be wrong.
[output stream 0:0 @ 0x1fb74e0] 1000 buffers queued in output stream 0:0, someth
ing may be wrong.
[output stream 0:0 @ 0x1fb74e0] 10000 buffers queued in output stream 0:0, somet
hing may be wrong.
Received signal 2: terminating.
^C

[ami_stuff]

Fixed in 807fa714f05c584ac027c36841315cea98f329d3.

adpcmdec: Fix OOM/infloop