avformat/avidec: recognize H265 fourcc as hevc

Fixes decoding of came2_2020-01-13__20-38-58_21-00-00__Chn2.avi

libavformat/avidec.c

@@ -832,6 +832,9 @@ FF_ENABLE_DEPRECATION_WARNINGS
                         st->need_parsing = AVSTREAM_PARSE_FULL;
                     if (st->codecpar->codec_id == AV_CODEC_ID_RV40)
                         st->need_parsing = AVSTREAM_PARSE_NONE;
+                    if (st->codecpar->codec_id == AV_CODEC_ID_HEVC &&
+                        st->codecpar->codec_tag == MKTAG('H', '2', '6', '5'))
+                        st->need_parsing = AVSTREAM_PARSE_FULL;
 
                     if (st->codecpar->codec_tag == 0 && st->codecpar->height > 0 &&
                         st->codecpar->extradata_size < 1U << 30) {

libavformat/riff.c

@@ -497,6 +497,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
 
 const AVCodecTag ff_codec_bmp_tags_unofficial[] = {
     { AV_CODEC_ID_HEVC,         MKTAG('H', 'E', 'V', 'C') },
+    { AV_CODEC_ID_HEVC,         MKTAG('H', '2', '6', '5') },
     { AV_CODEC_ID_NONE,         0 }
 };