vdec/lavc: fix H.265 decode with intra-refresh

Fix decoding of HEVC streams with intra-refresh and current Git FFmpeg
code. When intra-refresh is enabled and we are not catching the first
frame, no frame will be decoded without the flag
AV_CODEC_FLAG_OUTPUT_CORRUPT. This corresponds with FFmpeg commit
bc1a3bfd (2025-02-20), not yet included in current 7.1.1 / lavc 61,
should appear in lavc 62.

Steps to reproduce:
```
uv -t testcard -c lavc:e=libx265 -d gl
```

Author: MartinPulec

src/video_decompress/libavcodec.c

@@ -213,6 +213,7 @@ set_codec_context_params(struct state_libavcodec_decompress *s)
         bool req_low_delay = true;
         set_thread_count(s, &req_low_delay);
 
+        s->codec_ctx->flags |= AV_CODEC_FLAG_OUTPUT_CORRUPT;
         s->codec_ctx->flags |= req_low_delay ? AV_CODEC_FLAG_LOW_DELAY : 0;
         s->codec_ctx->flags2 |= AV_CODEC_FLAG2_FAST;
         // set by decoder