avcodec/flashsv: add FF_CODEC_CAP_INIT_CLEANUP to flashsv2

Fixes: memleaks on error paths during init
Fixes: 15548/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLASHSV2_fuzzer-6324019382452224

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/flashsv.c

@@ -585,6 +585,7 @@ AVCodec ff_flashsv2_decoder = {
     .close          = flashsv2_decode_end,
     .decode         = flashsv_decode_frame,
     .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP,
     .pix_fmts       = (const enum AVPixelFormat[]) { AV_PIX_FMT_BGR24, AV_PIX_FMT_NONE },
 };
 #endif /* CONFIG_FLASHSV2_DECODER */