avcodec/tests/jpeg2000dwt: Use 64bit in comparission

Found while reviewing: CID1500309 Unintentional integer overflow

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/tests/jpeg2000dwt.c

@@ -52,7 +52,7 @@ static int test_dwt(int *array, int *ref, int border[2][2], int decomp_levels, i
         return 1;
     }
     for (j = 0; j<MAX_W * MAX_W; j++) {
-        if (FFABS(array[j] - ref[j]) > max_diff) {
+        if (FFABS(array[j] - (int64_t)ref[j]) > max_diff) {
             fprintf(stderr, "missmatch at %d (%d != %d) decomp:%d border %d %d %d %d\n",
                     j, array[j], ref[j],decomp_levels, border[0][0], border[0][1], border[1][0], border[1][1]);
             return 2;