libc-19980524: unnecessary startup file dependencies on Hurd

[Roland McGrath]

> - Move libmachuser and libhurduser to the others pass.  mach and hurd get
> built before anything else, so the full C library should still be available
> by the time we need to link programs.

This might work, but I am a little dubious about it.  

> - Do the shared libraries other than libc really need an .interp section? 
> They aren't executable.  You could just take the dependency out and delete
> the reference in link-extra-lib.  I think the dependency is in extra-lib.mk.

You are right.  They are not executable, cannot be executable, and will not
be executable.  They could do without .interp altogether.