Linking fails on macOS with busybox error

[nathany]

Description of the bug:

On macOS, I'm running into an error with the link step on the sieve example (compile works fine).

What did you do, or what's a simple way to reproduce the bug?

./scripts/run_bazelisk.py run //toolchain -- link --output=sieve examples/sieve.o

What did you expect to happen?

successful link

What actually happened?

error: expected carbon-busybox symlink at `toolchain/install/prefix_root/bin/carbon`
error: linker command failed with exit code 1 (use -v to see invocation)

Any other information, logs, or outputs that you want to share?

Diagnostics:

/opt/homebrew/opt/llvm/bin/clang
clang-16 not found
Homebrew clang version 19.1.7
Target: arm64-apple-darwin24.3.0
Thread model: posix
InstalledDir: /opt/homebrew/Cellar/llvm/19.1.7_1/bin
Configuration file: /opt/homebrew/etc/clang/arm64-apple-darwin24.cfg
INFO: Invocation ID: 5e056cc8-b101-47d0-8314-50bfde1576f9
llvm_bindir = "/opt/homebrew/Cellar/llvm/19.1.7_1/bin"
/opt/homebrew/opt/llvm

trunk commit #97b234358e6f8a