retry_transfer_wrapper(): check for interrupt before operation

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
ff_network_wait_fd_timeout(): check for interrupt before operation

Reviewed-by: Lukasz M <lukasz.m.luki@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
av_frame_get_buffer: Do not fail when the channel layout is unknown

Fixes handling of cases with unknown layouts but known channel counts

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