New make target: "osxpkg" to create an Mac OS X installer package.

This patch adds a new make target, "osxpkg", to the main Makefile which
gereates a Apple Mac OS X installer package of ngIRCd. The packagemaker(1)
project bundle is stored in contrib/MacOSX/ngIRCd.pmdoc.

contrib/MacOSX/preinstall.sh

@@ -0,0 +1,25 @@
+#!/bin/sh
+# ngIRCd Mac OS X preinstall/preupgrade script
+
+LDPLIST="/Library/LaunchDaemons/de.barton.ngircd.plist"
+
+rm -f /tmp/ngircd_needs_restart || exit 1
+if [ -r "$LDPLIST" ]; then
+	echo "LaunchDaemon script found, checking status ..."
+	launchctl list | fgrep "de.barton.ngIRCd" >/dev/null 2>&1
+	if [ $? -eq 0 ]; then
+		# ngIRCd is already running; stop it and touch a
+		# "stamp file" so that we know that we have to
+		# restart it after installation/upgrade.
+		echo "ngIRCd is already running; stop it ..."
+		launchctl unload "$LDPLIST" || exit 1
+		echo "Daemon has been stopped."
+		touch /tmp/ngircd_needs_restart || exit 1
+	else
+		echo "ngIRCd is not running."
+	fi
+else
+	echo "LaunchDaemon script not found."
+fi
+
+# -eof-