lavfi: name anonymous structs
filtfmts: remove unused lavf include
utils: add yvyu422 to avcodec_align_dimensions2
h264: codec reinit: remove statements without effect

avctx->coded_{height,width} will always equal h->{height,width} since
init_dimensions() does that explicitly, Size changes are detected by
changes in mb_{height,width} earlier and propagated through the
needs_reinit variable.