`xxd` was recently moved out of `vim` to `xxd` package. As a result
`apt-dater` started failing the build as
https://hydra.nixos.org/build/247714641:
xxd -i apt-dater.xml > apt-dater.xml.inc
bash: line 1: xxd: command not found
The change pulls in missing `xxd` dependency.
While building nix on Darwin, I encountered an error in the `installCheckPhase`:
```
nix> building '/private/tmp/nix-build-nix-2.17.1.drv-1/nix-test/tests/fetchurl/store/mkc9z3arar02wi5jii655cjhdinx4npy-fetchurl.sh.drv'...
nix> waiting for children
nix> building of '/private/tmp/nix-build-nix-2.17.1.drv-1/nix-test/tests/fetchurl/store/mkc9z3arar02wi5jii655cjhdinx4npy-fetchurl.sh.drv^out' from .drv file: read 377 bytes
nix> objc[70707]: +[__NSCFConstantString initialize] may have been in progress in another thread when fork() was called.
nix> objc[70707]: +[__NSCFConstantString initialize] may have been in progress in another thread when fork() was called. We cannot safely call it or ignore it in the fork() child process. Crashing instead. Set a breakpoint on objc_initializeAfterForkError to debug.
nix> waiting for children
```
I noticed that #278802 should have addressed this problem, but it didn't.
The solution for me was to replace `yes` with `YES`.
As it turns out, most of the references to `OBJC_DISABLE_INITIALIZE_FORK_SAFETY` use `YES` instead of `yes`.
https://airflow.apache.org/blog/airflow-1.10.10/#running-airflow-on-macoshttp://sealiesoftware.com/blog/archive/2017/6/5/Objective-C_and_fork_in_macOS_1013.html
The objective C code that parses the environment variable is defined in
the function `environ_init` in [here](cd5e62a559/runtime/objc-runtime.mm (L265)) and it does
`*opt->var = (0 == strcmp(value, "YES"));`.
```
% nix-info -m
- system: `"aarch64-darwin"`
- host os: `Darwin 21.3.0, macOS 12.2.1`
- multi-user?: `yes`
- sandbox: `yes`
- version: `nix-env (Nix) 2.19.2`
- channels(hetzner): `"darwin, nixpkgs-22.05-darwin"`
- channels(root): `"darwin, nixpkgs-23.05-darwin"`
- nixpkgs: `/Users/hetzner/git/nixpkgs`
```
