buildworld: don't know how to make iterator.cc

[Randy Bush]

> I have this problem on two of my systems. Yesterday I was trying my
> weekly update on a i386 9.0 stable and had this failure. This morning
> on my i386 8.2 stable I had the same failure.
> 
> I csup'd the sources again and it found no changes. I the changed my
> supfile from mirro 10 to mirror 5 and it updated many source files. I
> am now in the process of building world and it has went well past the
> previous failure. I am assuming that it will complete, but if not I
> will follow up with another email.
> 
> It appears to just be a problem of an un-updated mirror.

confirmed.  hubs cc:d

randy