Remove the half-hearted attempt to make the utmp helper process drop

Remove the half-hearted attempt to make the utmp helper process drop
privileges just before dying of a fatal signal. I'm not sure what I
intended it for in the first place; it certainly isn't doing its job
properly (no setgid), it's causing compiler warnings due to not
checking the setuid return code, and we can't think of any useful
purpose for it.

[originally from svn r9766]