To achieve reproducible results, `cpio` archive members are added in
sorted order and inodes renumbered.
The `cpio-clean.pl` script is made obsolete by setting mtimes via
`touch` & using `cpio --reproducible`. Suggested by @dezgeg in
https://github.com/NixOS/nixpkgs/pull/21273#issuecomment-268116605.
Note that using `--reproducible` means that initial ramdisk creation now
requires at least `cpio` version 2.12 (released in 2015).
This comes from:
svn diff ^/nixpkgs/trunk/@18255 ^/nixpkgs/branches/stdenv-updates/ > diff
patch -p0 < diff
and then adding into svn all files new from the patch.
trunk@18255 comes from the last time I updated stdenv-updates from trunk.
svn path=/nixpkgs/stdenv-updates2/; revision=18272