axfer: add a common interface to handle a file with audio-specific data format

axfer: add a common interface to handle a file with audio-specific data format

Current aplay supports several types of data format for file; Microsoft/IBM
RIFF/Wave (.wav), Sparc AU (.au) and Creative Tech. voice (.voc). These
formats were designed to handle audio-related data with interleaved frame
alignment.

This commit adds a common interface to handle the file format, named as
'container' module. This includes several functions to build/parse
the format data from any file descriptors. Furthermore, this includes
several helper functions for implementations of each builder/parser.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>