Support mp3 in m3u

[Carl Eugen Hoyos]

(videolan ticket 9769)
vlc plays a "m3u" stream fine which contains a link to a mp3 stream, this fails with FFmpeg.

$ ffmpeg -i http://stream.krtu.org:9000/krtu_live-36kb.m3u
ffmpeg version N-57650-gcb52d6d Copyright (c) 2000-2013 the FFmpeg developers
  built on Oct 31 2013 01:03:43 with gcc 4.7 (SUSE Linux)
  configuration: --enable-gpl
  libavutil      52. 48.100 / 52. 48.100
  libavcodec     55. 39.100 / 55. 39.100
  libavformat    55. 19.104 / 55. 19.104
  libavdevice    55.  5.100 / 55.  5.100
  libavfilter     3. 90.100 /  3. 90.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
http://stream.krtu.org:9000/krtu_live-36kb.m3u: Invalid data found when processing input

The content of the m3u file which works fine is:

http://stream.krtu.org:9000/krtu_live-36kb

(works with mplayer -playlist)