* syscalls.cc (seteuid): Initialize pi.token before calling

    * syscalls.cc (seteuid): Initialize pi.token before calling
        internal_getlogin().
        * uinfo.cc (internal_getlogin): Use impersonation token instead
        of process token in case of active impersonation. Add some comments.
        (uinfo_init): Initializing myself->token and myself->impersonated
        before calling internal_getlogin(). Add some comments.