libtorch: 1.8.0 -> 1.8.1

[danieldk]

Motivation for this change

libtorch-bin: 1.8.0 -> 1.8.1

Changelog:
https://github.com/pytorch/pytorch/releases/tag/v1.8.1

libtorch-bin: fix false CUDA dependency in passthru test

The passthru test used the CUDA toolkit for the CUDA stub
unconditionally, also requiring the cudatoolkit derivation when
cudaSupport = false.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[r-rmcgibbo]

Result of nixpkgs-review pr 121380 at 0a2d3221 run on x86_64-linux 1

1 package built successfully:

• libtorch-bin

1 suggestion:

• warning: missing-phase-hooks

  installPhase should probably contain runHook preInstall and runHook postInstall.

  Near pkgs/development/libraries/science/math/libtorch/bin.nix:39:3:

     |
  39 |   installPhase = ''
     |   ^
  

[jonringer]

LGTM

Result of nixpkgs-review pr 121380 run on x86_64-linux 1

1 package built:

• libtorch-bin