Auto merge of #351 - kamalmarhubi:sleep, r=posborne
Auto merge of #351 - kamalmarhubi:sleep, r=posborne

unistd: Add sleep(3)

kamalmarhubi/nix-rust,asomers/nix,carllerche/nix-rust,nix-rust/nix,xd009642/nix,posborne/rust-nix,berkowski/nix,geofft/nix-rust,MarkusJais/nix-rust,geofft/nix-rust,Susurrus/nix,xd009642/nix,kamalmarhubi/nix-rust,berkowski/nix,posborne/rust-nix,carllerche/nix-rust,nix-rust/nix,Susurrus/nix,asomers/nix,nikklassen/nix-rust,nikklassen/nix-rust,posborne/rust-nix,carllerche/nix-rust,nikklassen/nix-rust,geofft/nix-rust,MarkusJais/nix-rust,xd009642/nix,MarkusJais/nix-rust,Susurrus/nix,kamalmarhubi/nix-rust,berkowski/nix