avcodec/eamad: silence uninitialized variable warnings

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/cinepakenc: Zero AVPictures, silence "may be used uninitialized" warnings

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/cinepakenc: drop coded_frame init

Fixes const being lost warning

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