tools/target_dec_fuzzer: Adjust threshold for dst

Fixes: Timeout (400sec -> 14sec)
Fixes: 18989/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DST_fuzzer-5175008116867072

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

tools/target_dec_fuzzer.c

@@ -140,6 +140,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     case AV_CODEC_ID_BINKVIDEO: maxpixels /= 32; break;
     case AV_CODEC_ID_CFHD:      maxpixels /= 128; break;
     case AV_CODEC_ID_DIRAC:     maxpixels /= 8192; break;
+    case AV_CODEC_ID_DST:       maxsamples /= 8192; break;
     case AV_CODEC_ID_DXV:       maxpixels /= 32;  break;
     case AV_CODEC_ID_FFWAVESYNTH: maxsamples /= 16384; break;
     case AV_CODEC_ID_MSRLE:     maxpixels /= 16;  break;