darwin.libtapi: Build with libcxxStdenv on non-Darwin

[zhaofengli]

Description of changes

This PR fixes linking in cctools-port which is built with libcxxStdenv. There is no rebuild on Darwin and fixes darwin.cctools on non-Darwin.

Without this, C++ ABI says hi (and we don't want them to say hi 😛):

/nix/store/22p5nv7fbxhm06mfkwwnibv1nsz06x4b-binutils-2.40/bin/ld: textstub_dylib_file.cpp:(.text._ZN8textstub5dylib4FileI8arm64_32E4initEPN4tapi2v119LinkerInterfaceFileEPK7OptionsbbbbPKcRKN2ld10VersionSetESC_bbbb[_ZN8textstub5dylib4FileI8arm64_32E4initEPN4tapi2v119LinkerInterfaceFileEPK7OptionsbbbbPKcRKN2ld10VersionSetESC_bbbb]+0x88d): undefined reference to `tapi::v1::LinkerInterfaceFile::ignoreExports() const'

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• 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/)
• 23.05 Release Notes (or backporting 22.11 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.

[zhaofengli]

No longer needed since #307880. Tested that libtapi builds on x86_64-linux.