nix build: Don't create output links with --dry-run.
nix build: Don't create output links with --dry-run.

Fixes #1849.

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