Remove lowres video decoding

This feature is complex, of questionable utility, and slows down
normal decoding.

Signed-off-by: Mans Rullgard <mans@mansr.com>

libavcodec/h261dec.c

@@ -651,6 +651,5 @@ AVCodec ff_h261_decoder = {
     .close          = h261_decode_end,
     .decode         = h261_decode_frame,
     .capabilities   = CODEC_CAP_DR1,
-    .max_lowres     = 3,
     .long_name      = NULL_IF_CONFIG_SMALL("H.261"),
 };