anchor.diff:  let
   
     libc = if stdenv.cc.libc or null != null then stdenv.cc.libc else "/usr";
  -
  +  libcInc = libc.dev or libc;
  +  libcLib = libc.out or libc;
   in
   
   with stdenv.lib;
  
positive.code:     unset LD_LIBRARY_PATH
    '';
  
    postInstall =
      ''
        # Remove dependency between "out" and "man" outputs.
        rm $out/lib/perl5/*/*/.packlist
  
        # Remove dependencies on glibc.dev and coreutils.
        substituteInPlace $out/lib/perl5/*/*/Config_heavy.pl \
          --replace ${stdenv.glibc.dev or "/blabla"} /no-such-path \
          --replace $man /no-such-path
      ''; # */
  
    meta = {
  
negative.code:       "-Uinstallusrbinperl"
        "-Dinstallstyle=lib/perl5"
        "-Duseshrplib"
        "-Dlocincpth=${libcInc}/include"
        "-Dloclibpth=${libcLib}/lib"
      ]
      ++ optional enableThreading "-Dusethreads";
  
  