FILE_ID_INFO is redefined when using MinGW-w64 version 9.0.0

A few days MinGW-w64 version 9.0.0 was released.

I have built the latest GCC and LLVM toolchains against it (see https://winlibs.com/) and tried to build Qt with it.

It works except for one issue: FILE_ID_INFO and PFILE_ID_INFO are redefined in qtbase/src/corelib/io/qfilesystemengine_win.cpp.

I was able to solve the issue by changing:

#if defined(Q_CC_MINGW) && WINVER < 0x0602 // Windows 8 onwards
typedef struct _FILE_ID_INFO {
  ULONGLONG VolumeSerialNumber;
  FILE_ID_128 FileId;
} FILE_ID_INFO, *PFILE_ID_INFO;
#endif // if defined (Q_CC_MINGW) && WINVER < 0x0602

to:

#if defined(Q_CC_MINGW) && WINVER < 0x0602 && !(_WIN32_WINNT >= _WIN32_WINNT_WIN8) // Windows 8 onwards
typedef struct _FILE_ID_INFO {
  ULONGLONG VolumeSerialNumber;
  FILE_ID_128 FileId;
} FILE_ID_INFO, *PFILE_ID_INFO;
#endif // if defined (Q_CC_MINGW) && WINVER < 0x0602

This way it builds, but to know if this is the best way to patch it you need to make sure it doesn't break MSVC builds.

I had the same issue with Qt 5.15.2 and Qt 6.1.0, and both times this solution worked.