tests: add fate-lavfi-il test
lavd/v4l2: implement consistent error handling

In particular, avoid use of non-thread-safe strerror(), and store errno
before calling av_log().
pcx: use init_get_bits8()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
pcx: Add missing padding to scanline buffer

Fixes out of array read

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