tools/target_dec_fuzzer: adjust threshold for arbc

Fixes: Timeout (63sec -> 48ms)
Fixes: 31886/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ARBC_fuzzer-5287235705503744

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

tools/target_dec_fuzzer.c

@@ -152,6 +152,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     maxsamples = maxsamples_per_frame * maxiteration;
     switch (c->id) {
     case AV_CODEC_ID_AGM:         maxpixels  /= 1024;  break;
+    case AV_CODEC_ID_ARBC:        maxpixels  /= 1024;  break;
     case AV_CODEC_ID_BINKVIDEO:   maxpixels  /= 32;    break;
     case AV_CODEC_ID_CFHD:        maxpixels  /= 128;   break;
     case AV_CODEC_ID_COOK:        maxsamples /= 1<<20; break;