rust: include the rustc-dev component

[symphorien]

This enables to compile rls and rustc

See also rust-lang/rust#64823

Fixes #77108 and probably #77358

I tested a version of this patch with more debugging, but I didn't want to do yet another 3+ hour build just to check that it still works without set -x.

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.

[curiousleo]

This fixes #77358. I'm in favour of getting this merged into master, but I'm not sure what the procedure for that is. I'd appreciate it if whoever gives the go-ahead for merging this change into master could ping this PR so I'm aware. Thanks!

[LnL7]

This will end up in master with the staging-next iteration after #77047, along with everything else that was merged to staging since.

[curiousleo]

This will end up in master with the staging-next iteration after #77047, along with everything else that was merged to staging since.

I can't see anything related to rust in https://github.com/NixOS/nixpkgs/pull/77047/commits or https://github.com/NixOS/nixpkgs/pull/77047/files.

[LnL7]

This was created after the current iteration started, it will be included in the next one.