tiff: correctly decode saparate planes with horizontal differencing predictor

Closes #2648.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
jpeg2000dec: fix av_log()

Found-by: ubitux
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
jpeg2000: Zero prec->cblk

Prevent use of uninitialized memory / valgrind failure

Found-by: ubitux
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavc: add ONLY_IF_THREADS_ENABLED where it is missing

Signed-off-by: Paul B Mahol <onemda@gmail.com>
tiff: simplify picking right pixel format

Signed-off-by: Paul B Mahol <onemda@gmail.com>
Add unscaled converter from GBRP > 8bit to RGBx48/64.

Fixes ticket #2633.

Tested-by: Michael Cinquin
lavfi/lut3d: add sanity checks.

Should fix CID1026775 and CID1026774.