Remove -nostdlibinc flag from clang when building for android-prebuilt

[alexfmpe]

#356162 caused libffi, gmp, hello and likely others to fail for pkgsCross.aarch64-android-prebuilt with errors about standard headers.

> ../src/closures.c:418:10: fatal error: 'sys/types.h' file not found
> #include <sys/types.h>

Looking at the pre-existing comment, I don't see how my /usr/include would be relevant given I'm building from nixos, so it's likely this is sysroot related, and indeed the standard files can be seen in

ls $(nix-build -A pkgsCross.aarch64-android-prebuilt.buildPackages.androidndkPkgs.binaries)/toolchain/sysroot/usr/include`

IIUC this is a workaround that actually re-introduces the leaking concern for non-nixos, but I don't know what the proper fix is nor why this surfaced on android in particular.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

---

Add a 👍 reaction to pull requests you find important.

[alexfmpe]

cc @pwaller (apparenty can't add as reviewer?)

[emilazy]

Is this the prebuilt Android toolchain? It presumably regressed because it was previously in an LLVM patch, which don’t get applied to prebuilt toolchains.

[pwaller]

Not knowing much about the android toolchain and how it is wired in nixpkgs, looks like a reasonable fix to me to get things working again at least.

The with -nostdlibinc nix cc wrapper assumes that it is feeding the stdlib paths into the compiler. If that's not the case, as appears here, then -nostdinc is not wanted.

[drupol]

This PR broke the linter CI. Going to provide a fix now.

[drupol]

Fix @ #402978

[drupol]

@alexfmpe

Thank you for the PR, but next time make sure to follow the commit convention and PR title, I think this would have been avoided.

In the meantime, don't worry, I've fixed it.

[alexfmpe]

Oh lint was green when I first opened, didn't notice there were new nix-fmt rules since then.

make sure to follow the commit convention and PR title, I think this would have been avoided.

Do you mean prefixing with cc-wrapper: ? True, I did forget that, but I'm a bit lost on how that relates to the lint issue?