Support for playing WAV files with "extensible format" header using aplay.

Support for playing WAV files with "extensible format" header using aplay.

WAV files with more than 2 channels or with more than 16 bits per samples
can be saved with "extensible format" chunk
(see http://msdn2.microsoft.com/en-us/library/ms713496(VS.85).aspx).
For instance, sox, when converting data to 24- or 32-bits per sample format
uses this format, and aplay was unable to play such file. Now the problem
is solved :-)

Signed-off-by: Pawel MOLL <pawel.moll@st.com>