ljpeg: support files with interval in MCU-rows different than 0

[ami_stuff]

I will attache ljpeg files with "restart interval in MCU-rows" option set to 0, 1, 25 and 50. Currently FFmpeg can correctly decode files when this option is set to 0.

I created attached files with "ImageConverter Plus" and then loaded them to "PICTools Apollo" to confirm that the files are correct.

ffmpeg -i mcu50.jpg out.tif
ffmpeg version 0.9.0.git-dc7ad85, Copyright (c) 2000-2012 the FFmpeg developers
  built on Jan  4 2012 22:15:52 with gcc 4.5.0
  libavutil      51. 34.100 / 51. 34.100
  libavcodec     53. 50.100 / 53. 50.100
  libavformat    53. 29.100 / 53. 29.100
  libavdevice    53.  4.100 / 53.  4.100
  libavfilter     2. 57.101 /  2. 57.101
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0.  5.100 /  0.  5.100
  libpostproc    51.  2.100 / 51.  2.100
[mjpeg @ 0x11573ab0] Warning: not compiled with thread support, using thread emulation
Input #0, image2, from 'mcu50.jpg':
  Duration: 00:00:00.04, start: 0.000000, bitrate: N/A
Codec 0x8 is not in the full list.
    Stream #0:0: Video: mjpeg, bgr24, 639x479, 25 tbr, 25 tbn, 25 tbc
Incompatible pixel format 'bgr24' for codec 'tiff', auto-selecting format 'rgb24'
[buffer @ 0x11576330] w:639 h:479 pixfmt:bgr24 tb:1/1000000 sar:0/1 sws_param:
[buffersink @ 0x115766b0] auto-inserting filter 'auto-inserted scale 0' between the filter 'src' and the filter 'out'
[scale @ 0x11576c30] w:639 h:479 fmt:bgr24 -> w:639 h:479 fmt:rgb24 flags:0x4
[tiff @ 0x115752b0] Warning: not compiled with thread support, using thread emulation
[mjpeg @ 0x11573ab0] Warning: not compiled with thread support, using thread emulation
Output #0, image2, to 'out.tif':
  Metadata:
    encoder         : Lavf53.29.100
Codec 0x62 is not in the full list.
    Stream #0:0: Video: tiff, rgb24, 639x479, q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg -> tiff)
Press [q] to stop, [?] for help
frame=    1 fps=  0 q=0.0 Lsize=       0kB time=00:00:00.04 bitrate=   0.0kbits/s    
video:905kB audio:0kB global headers:0kB muxing overhead -100.000000%

[Michael Niedermayer]

Locally fixed

[ami_stuff]

@michael

Do you get colorful vertical line on the right side with MCU1.jpg?

ffmpeg -i mcu1.jpg out.bmp

the rest of the files decodes correctly here except this one