Since wine commit 401288a7 (make_specfiles: Generate a list of
syscalls from the corresponding spec files., 2023-11-16), spec files
are used to auto-generate the following files:

- dlls/ntdll/ntsyscalls.h (from dlls/ntdll/ntdll.spec)
- dlls/win32u/win32syscalls.h (from dlls/win32u/win32u.spec)