tools/target_dec_fuzzer: Add threshold for ALS

Fixes: Timeout (253sec -> 16sec)
Fixes: 18668/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-6227155369590784

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

@@ -150,6 +150,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     case AV_CODEC_ID_INDEO4:      maxpixels  /= 128;   break;
     case AV_CODEC_ID_LSCR:        maxpixels  /= 16;    break;
     case AV_CODEC_ID_MOTIONPIXELS:maxpixels  /= 256;   break;
+    case AV_CODEC_ID_MP4ALS:      maxsamples /= 65536; break;
     case AV_CODEC_ID_MSRLE:       maxpixels  /= 16;    break;
     case AV_CODEC_ID_MSS2:        maxpixels  /= 16384; break;
     case AV_CODEC_ID_MSZH:        maxpixels  /= 128;   break;