tools/target_dec_fuzzer: Adjust threshold for DXV

Fixes: TImeout (20sec -> 4sec)
Fixes: 17735/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DXV_fuzzer-5723368317255680

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

@@ -139,6 +139,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         // Allows a small input to generate gigantic output
     case AV_CODEC_ID_BINKVIDEO: maxpixels /= 32; break;
     case AV_CODEC_ID_DIRAC:     maxpixels /= 8192; break;
+    case AV_CODEC_ID_DXV:       maxpixels /= 32;  break;
     case AV_CODEC_ID_MSRLE:     maxpixels /= 16;  break;
     case AV_CODEC_ID_QTRLE:     maxpixels /= 16;  break;
     case AV_CODEC_ID_SANM:      maxpixels /= 16;  break;