xinit: include launchd files when sandboxed

In sandbox, `autoconf` can't detect presence of `/sbin/launchd`, which
makes the derivation not include `launchd` specific files. Later,
`xquartz` fails because it relies on these files being present in
`xinit` output.

This patch forces installation of these files regardless of whether the
`launchd` binary is seen in the build environment.

pkgs/by-name/xi/xinit/package.nix

@@ -56,6 +56,7 @@ stdenv.mkDerivation (finalAttrs: {
     "--with-xserver=${xorg-server.out}/bin/X"
   ]
   ++ lib.optionals stdenv.hostPlatform.isDarwin [
+    "--with-launchd=yes"
     "--with-bundle-id-prefix=org.nixos.xquartz"
     "--with-launchdaemons-dir=${placeholder "out"}/LaunchDaemons"
     "--with-launchagents-dir=${placeholder "out"}/LaunchAgents"