Make autogen.man reproducible
Make autogen.man reproducible

Keep the date format similar to what it is when we are not using the
MAN_PAGE_DATE env var. The man pages scripts seem to use different
formats in different pages, so we use the most common format for all.

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