takdec: simplify use of scalarproduct_int16 in decode_subframe()

Makes decoding little faster.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
sws/output: silence warnings about uninitialized use of variables

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
mimic: Fix race condition

Fixes access after free.

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