rtmp: support the AMF_DATE tag

Instead of returning EINVAL, which can cause a stream to fail to load, this
allows the tag to be passed through to the flv demuxer, where it's summarily
ignored.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/rtmppkt.c

@@ -440,6 +440,7 @@ int ff_amf_tag_size(const uint8_t *data, const uint8_t *data_end)
     case AMF_DATA_TYPE_STRING:      return 3 + AV_RB16(data);
     case AMF_DATA_TYPE_LONG_STRING: return 5 + AV_RB32(data);
     case AMF_DATA_TYPE_NULL:        return 1;
+    case AMF_DATA_TYPE_DATE:        return 11;
     case AMF_DATA_TYPE_ARRAY:
         parse_key = 0;
     case AMF_DATA_TYPE_MIXEDARRAY: