postproc/postprocess: Remove unused argument from reallocAlign()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
postproc/postprocess: Use FF_ARRAY_ELEMS() in pp_free_context() instead of hard-coding their size

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
postproc/postprocess: remove redundant casts

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