flvenc: Don't pretend to support muxing "plain" VP6

The plain VP6 format is vertically flipped compared to VP6F/VP6A.
Support for the plain VP6 format was added in 09d8c0ae (which
also introduced support for muxing VP6F properly in general).
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/flvenc.c

@@ -35,7 +35,6 @@ static const AVCodecTag flv_video_codec_ids[] = {
     { AV_CODEC_ID_FLASHSV,  FLV_CODECID_SCREEN },
     { AV_CODEC_ID_FLASHSV2, FLV_CODECID_SCREEN2 },
     { AV_CODEC_ID_VP6F,     FLV_CODECID_VP6 },
-    { AV_CODEC_ID_VP6,      FLV_CODECID_VP6 },
     { AV_CODEC_ID_H264,     FLV_CODECID_H264 },
     { AV_CODEC_ID_NONE,     0 }
 };
@@ -437,7 +436,7 @@ static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
     uint8_t *data = NULL;
     int flags = 0, flags_size;
 
-    if (enc->codec_id == AV_CODEC_ID_VP6 || enc->codec_id == AV_CODEC_ID_VP6F ||
+    if (enc->codec_id == AV_CODEC_ID_VP6F ||
         enc->codec_id == AV_CODEC_ID_AAC)
         flags_size = 2;
     else if (enc->codec_id == AV_CODEC_ID_H264)
@@ -527,8 +526,6 @@ static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
         avio_wb32(pb, data_size + 11);
     } else {
         avio_w8(pb,flags);
-        if (enc->codec_id == AV_CODEC_ID_VP6)
-            avio_w8(pb, 0);
         if (enc->codec_id == AV_CODEC_ID_VP6F)
             avio_w8(pb, enc->extradata_size ? enc->extradata[0] : 0);
         else if (enc->codec_id == AV_CODEC_ID_AAC)