* On Darwin, don't link Perl against /usr/lib/libutil.dylib. Libutil

  uses /usr/lib/libstdc++.dylib, and so we get segfaults when using
  Perl modules that depend on another libstdc++.dylib (like Nix's Perl
  bindings).  It doesn't appear that libutil provides useful
  functionality for Perl on Darwin.

svn path=/nixpkgs/branches/stdenv-updates/; revision=32364