Do not import libc structs directly.
Do not import libc structs directly.

That allows us to import sigaction on older rust versions.

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