nkf: pull upstream fix for parallel build failure
nkf: pull upstream fix for parallel build failure

Without the change parallel build fails as:

    cp -f nkf ...-nkf-2.1.5/bin/
    mkdir ...-nkf-2.1.5/man/ja
    mkdir: cannot create directory '...-nkf-2.1.5/man/ja': No such file or directory

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs