libaacplus: support for float sample format

Signed-off-by: Paul B Mahol <onemda@gmail.com>
mjpegdec: fix overlapping memcpy with upscale_v

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>