Add a launchd configuration file to run nix-daemon

Makefile

@@ -17,6 +17,7 @@ makefiles = \
   scripts/local.mk \
   corepkgs/local.mk \
   misc/systemd/local.mk \
+  misc/launchd/local.mk \
   misc/upstart/local.mk \
   misc/emacs/local.mk \
   doc/manual/local.mk \

misc/launchd/local.mk

+ifeq ($(OS), Darwin)
+
+  $(eval $(call install-data-in, $(d)/org.nixos.nix-daemon.plist, $(prefix)/Library/LaunchDaemons))
+
+endif

misc/launchd/org.nixos.nix-daemon.plist.in

+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+  <dict>
+    <key>Label</key>
+    <string>org.nixos.nix-daemon</string>
+    <key>RunAtLoad</key>
+    <true/>
+    <key>Program</key>
+    <string>@bindir@/nix-daemon</string>
+    <key>StandardErrorPath</key>
+    <string>/var/log/nix-daemin.log</string>
+    <key>StandardOutPath</key>
+    <string>/dev/null</string>
+  </dict>
+</plist>