lavfi/interlace: remove now unused av_opt_free() call

Signed-off-by: Paul B Mahol <onemda@gmail.com>
avutil/avutil_version: Run checks just once

This ensures that applications that call avutil_version() often
would not run the checls every time

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/c93: Check for block overlap.

Fixes overlapping memcpy()

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