tools/target_dec_fuzzer: Adjust threshold for flac

Fixes: Timeout
Fixes: 31464/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLAC_fuzzer-4843965653319680

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

@@ -159,6 +159,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     case AV_CODEC_ID_DST:         maxsamples /= 1<<20; break;
     case AV_CODEC_ID_DXV:         maxpixels  /= 32;    break;
     case AV_CODEC_ID_FFWAVESYNTH: maxsamples /= 16384; break;
+    case AV_CODEC_ID_FLAC:        maxsamples /= 1024;  break;
     case AV_CODEC_ID_FLV1:        maxpixels  /= 1024;  break;
     case AV_CODEC_ID_G2M:         maxpixels  /= 1024;  break;
     case AV_CODEC_ID_GDV:         maxpixels  /= 512;   break;