PING [4.1 regression, patch] build i686-pc-mingw32

[DJ Delorie]

> Presumably, people with blanket write privs and people responsible for
> the build machinery.

Yup, that's them.

I did a little historical digging on this item, and the original
trigger was http://gcc.gnu.org/ml/gcc-patches/2005-05/msg00280.html
where Paolo needed to switch from symlinks to hardlinks for toplevel
bootstrapping.  So, I think we've confused the issue enough that we
may be making bad decisions (or at least *I* am confused and may make
bad decisions ;).

Paolo, could you go back and think about the bootstrapping problem
from MinGW's perspective?

Danny, could you summarize which build features MinGW supports?  (I
assume cp and $(SHELL) but not symlinks, hardlinks, or #!).  DJGPP and
Cygwin shouldn't be a problem here; they both support symlinks and #!
but I don't think they support hardlinks.