Doesn't compile on Windows

This program does not compile on Microsoft Windows 11:
```
Microsoft (R) C/C++ optimizing compiler version 19.41.34123 for x86
(C) Microsoft Corporation.  All rights reserved.

raw2iso.c
raw2iso.c(120): error C2057: constant expression required
raw2iso.c(120): error C2466: cannot allocate memory for a constant zero-size array
raw2iso.c(120): error C2133: sector: unknown size
```