Fixes gapless playback

[dimitris-c]

Fixes gapless playback for FLAC files.

The issue was hidden in the details, especially in the comment header of the AudioFileStreamParseBytes as pointed out by an Apple Engineer on the feedback assistant.

As documented in AudioFileStream.h for the function AudioFileStreamParseBytes:

	At the end of the stream, this function must be called once with null data pointer and zero
	data byte size to flush any remaining packets out of the parser.