verify: Fix the bad pattern block offset value

We offset buf by header_size for pattern verification. Add header_size
to the mismatched buf offset to get the correct block offset value.

Signed-off-by: Igor Pylypiv <ipylypiv@google.com>

verify.c

@@ -398,7 +398,8 @@ static int verify_io_u_pattern(struct verify_header *hdr, struct vcont *vc)
  (unsigned char)buf[i],
  (unsigned char)pattern[mod],
  bits);
- log_err("fio: bad pattern block offset %u\n", i);
+ log_err("fio: bad pattern block offset %u\n",
+ i + header_size);
  vc->name = "pattern";
  log_verify_failure(hdr, vc);
  return EILSEQ;