@c Open a directory for listing
This function implements the opendir function of UNIX. The difference between this implementation and the UNIX version is that this implementation requires a DIR structure to be passed as an argument. The reason for this is that the Windows system calls do not allocate memory and pass return values in structures allocated by the caller. Because we did not want to implement memory allocation in these routines we followed the Windows like way.
The first argument pszDirectoryName is a ZCAR directory name to be scanned. The second argument is an allocated DIR structure that has to be valid until the file_closedir is called.
The second parameter under UNIX is not used. However to be safe and portable to Win32 the parameter
should be handled with care.
DIR *file_opendir(char *pszDirectoryName,