Loads the specified account from disk. This function is called by the
system. Under any normal circumstances, you won't need to call it.
Parameters:
whose - The canonical form of the user ID to load. You can use usr_exists()to obtain this.
uacc - A pointer to a pre-allocated useracc_tto hold the
account structure.
Returns:
Zero if the user could not be loaded, in which case, errno
will be set to the error reported by the system. One if the user was loaded
successfully, in which case the account will be in uacc.