aacdec: Don't count probed ADTS frames if there are false positives

If a portion of the probe buffer seem to resemble ADTS frames,
but some data at the end is a mismatch, disregard the whole
probing attempt. If it actually is ADTS data, there shouldn't be
any mismatches within the sequential frame data.

Signed-off-by: Martin Storsjö <martin@martin.st>
aacdec: Lower the number of frames required to detect ADTS

For live audio streams, requiring 500 frames for a stream to
be detected is a bit overkill.

This allows live ADTS streams that don't start nicely at
a frame boundary to start up more quickly, e.g.
http://mp3.streampower.be/radio1.aac.

Signed-off-by: Martin Storsjö <martin@martin.st>