avcodec/x86/lossless_audiodsp: support len %16 == 8 in scalarproduct_and_madd_int16()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/wmalosslessdec: support 24bit lossless

Not checked if its actually lossless
Fixes Ticket1847

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>