avformat: Move av_probe_input* to format.c
avstring: Expose the simple name match function

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
avformat: Use the mime type information in input probe

It should provide a quicker guess for elementary streams provided
by http.
aac: Register the mime type

Speed up probing ADTS live streams that are not frame-aligned such
as http://mp3.streampower.be/radio1.aac .
matroska: Register mime types