buildGoPackage: Respect passing CGO_ENABLED explicitly
buildGoPackage: Respect passing CGO_ENABLED explicitly

This used to work but was broken by 6a27d63a882d1daecd1dce9e61135ccea3b0696e.

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