This function changes the file permissions. It has the same function of the shell command chmod.
Pointer to a valid FileOperations class.
The file/dir name to work on
The new file permissions
should return AFC_ERR_NO_ERROR
If chmod fails, you may get AFC_FILEOPS_ERR_CHMOD, but only if you set that chmod errors are blocking with afc_fileops_set_tag()
This function may or may not return an error value in case of real errors, depending on the settings you have made using afc_fileops_set_tag() or afc_fileops_set_tags()