avutil/pixdesc: remove unneeded assignment

Found-by: CSA
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/trim: remove duplicate assignment

Found-by: CSA
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avdevice/oss_audio: Check SNDCTL_DSP_GETFMTS failure, print a warning but continue

Found-by: CSA and Timothy Gu <timothygu99@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>