avcodec/adpcm: Check initial predictor for ADPCM_IMA_EA_EACS

Fixes: signed integer overflow: -2147483360 - 631 cannot be represented in type 'int'
Fixes: 17701/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ADPCM_IMA_EA_EACS_fuzzer-5711517319692288

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 2f66e8436d)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/adpcm.c

@@ -1138,8 +1138,11 @@ static int adpcm_decode_frame(AVCodecContext *avctx, void *data,
                 return AVERROR_INVALIDDATA;
             }
         }
-        for (i=0; i<=st; i++)
+        for (i=0; i<=st; i++) {
             c->status[i].predictor  = bytestream2_get_le32u(&gb);
+            if (FFABS(c->status[i].predictor) > (1<<16))
+                return AVERROR_INVALIDDATA;
+        }
 
         for (n = nb_samples >> (1 - st); n > 0; n--) {
             int byte   = bytestream2_get_byteu(&gb);