fate/checkasm: fix use of uninitialized memory on hevc_add_res tests

tests/checkasm/hevc_add_res.c

@@ -59,7 +59,7 @@ static void check_add_res(HEVCDSPContext h, int bit_depth)
         randomize_buffers(res0, size);
         randomize_buffers2(dst0, size);
         memcpy(res1, res0, sizeof(*res0) * size);
-        memcpy(dst1, dst0, size);
+        memcpy(dst1, dst0, sizeof(int16_t) * size);
 
         if (check_func(h.add_residual[i - 2], "add_res_%dx%d_%d", block_size, block_size, bit_depth)) {
             call_ref(dst0, res0, stride);