[Nix-dev] libiconv on non-GNU systems

[Yury G. Kudryashov]

Hi!

# grep libiconv all-packages.nix
    libiconv = if stdenv.isDarwin then libiconv else null;
      zlib curl gd postgresql openssl pkgconfig sqlite getConfig libiconv 
libjpeg libpng;
    libiconv = if (stdenv.system == "i686-freebsd") then libiconv else null;
      libiconv = if stdenv.system == "i686-freebsd" then libiconv else null;
      libiconv = if stdenv.system == "i686-freebsd" then libiconv else null;
  libiconv = callPackage ../development/libraries/libiconv { };

Which test should be used instead of all these? I'm going to unify all these 
tests into something like

libiconvPkg = callPackage ...;
libiconv = if ... then libiconvPkg else stdenv.gcc.libc;

Then use libiconv everywhere else without re-checking.