wmav2 in wav: fix timer when seeking

[ami_stuff]

mplayer/wmp can seek correctly in the file

 http://samples.mplayerhq.hu/A-codecs/WMA/wav/FLCL_Ending_My.wav

C:\>ffmpeg -i FLCL_Ending_My.wav
ffmpeg version N-46283-g1475815 Copyright (c) 2000-2012 the FFmpeg developers
  built on Nov  2 2012 02:31:20 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.  1.100 / 52.  1.100
  libavcodec     54. 70.100 / 54. 70.100
  libavformat    54. 35.100 / 54. 35.100
  libavdevice    54.  3.100 / 54.  3.100
  libavfilter     3. 21.106 /  3. 21.106
  libswscale      2.  1.102 /  2.  1.102
  libswresample   0. 16.100 /  0. 16.100
  libpostproc    52.  1.100 / 52.  1.100
[wav @ 0x1edc340] Estimating duration from bitrate, this may be inaccurate
Guessed Channel Layout for  Input Stream #0.0 : stereo
Input #0, wav, from 'FLCL_Ending_My.wav':
  Duration: 00:02:19.94, bitrate: 64 kb/s
    Stream #0:0: Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, stereo, fltp, 64
kb/s
At least one output file must be specified

[cehoyos]

Seeking works (at least to a certain degree), the timer in the status line is wrong - it stays unchanged on seeking, also reproducible with mplayer -demuxer lavf

$ ffplay FLCL_Ending_My.wav
ffplay version N-46747-ga1b5c96 Copyright (c) 2003-2012 the FFmpeg developers
  built on Nov 15 2012 09:06:47 with gcc 4.7 (SUSE Linux)
  configuration: 
  libavutil      52.  6.100 / 52.  6.100
  libavcodec     54. 72.100 / 54. 72.100
  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
[wav @ 0x7fce480008c0] Estimating duration from bitrate, this may be inaccurate
Input #0, wav, from 'FLCL_Ending_My.wav':
  Duration: 00:02:19.94, bitrate: 64 kb/s
    Stream #0:0: Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, 2 channels, fltp, 64 kb/s
Seek to 75% ( 0:01:43) of total duration ( 0:02:19)
   2.86 A-V:  0.000 fd=   0 aq=   24KB vq=    0KB sq=    0B f=0/0

[cehoyos]

Regression since 6c65cf5 / f095391.