cmdutils/filter_codec_opts: do not discard all options for CODEC_ID_NONE

This fixes cases where the codec is detect later than the stream creation
No testcase with unmodified source known

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/lavfutils: call av_find_stream_info() before reading various information about the stream

No testcase with unmodified source is known

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