avformat/ty: rec_size seems to only need 32bit

May help CID1604560 Overflowed integer argument

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit be30913538)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/ty.c

@@ -47,7 +47,7 @@ static const uint8_t ty_AC3AudioPacket[]  = { 0x00, 0x00, 0x01, 0xbd };
 #define CHUNK_PEEK_COUNT  3      /* number of chunks to probe */
 
 typedef struct TyRecHdr {
-    int64_t   rec_size;
+    int32_t   rec_size;
     uint8_t   ex[2];
     uint8_t   rec_type;
     uint8_t   subrec_type;