Canonicalize gids to 0
Canonicalize gids to 0

Previously files in the Nix store were owned by root or by nixbld,
depending on whether they were created by a substituter or by a
builder. This doesn't matter much, but causes spurious diffoscope
differences. So use root everywhere.

rycee/nix,dtzWill/nix,dezgeg/nix,rycee/nix,zimbatm/nix,dezgeg/nix,ehmry/nix,NixOS/nix,pikajude/nix,rycee/nix,vcunat/nix,shlevy/nix,wmertens/nix,pikajude/nix,wmertens/nix,ehmry/nix,peti/nix,rycee/nix,ehmry/nix,layus/nix,dezgeg/nix,shlevy/nix,wmertens/nix,dtzWill/nix,peti/nix,peti/nix,wmertens/nix,zimbatm/nix,NixOS/nix,vcunat/nix,layus/nix,vcunat/nix,dezgeg/nix,zimbatm/nix,dezgeg/nix,ysangkok/nix,layus/nix,ysangkok/nix,ehmry/nix,vcunat/nix,shlevy/nix,layus/nix,ehmry/nix,peti/nix,NixOS/nix,bennofs/nix,peti/nix,bennofs/nix,shlevy/nix,bennofs/nix,dtzWill/nix,ehmry/nix,rycee/nix,pikajude/nix,NixOS/nix,zimbatm/nix,NixOS/nix,dtzWill/nix,bennofs/nix,dtzWill/nix,ysangkok/nix,layus/nix,shlevy/nix