Modern WAV files may contain extra chunks before the FMT header,
as specified in the Broadcast Wave Format extension.
These chunks must be skipped to properly read the header.
Backyard Baseball 2003 was missing dialog which was lip-synced to
animation. This was due to it using the WAV block alignment as a count
of bytes per sample. This is not true for the IMA ADPCM format used for
speech in Backyard Baseball 2003.
This allows raw PCM in WAVE containers to have duration and be
seekable, and opens the door for ADPCM streams to be seekable later
if necessary.
This change is needed to avoid duplication of RIFF/WAVE container
parsing for SCI engine, which uses raw PCM WAVE files and needs to
be able to determine their lengths.
