Updated lsyncd formula to work with OS X 10.9.1

Added support for an updated OS X Mavericks 10.9.1. xnu package version remains the same, but xnu_headers hash required this update to work correctly.

Without this fix lsyncd can't be installed on 10.9.1
<pre>
[anayden ~]$ brew install lsyncd
==> Downloading https://github.com/axkibe/lsyncd/archive/release-2.1.5.tar.gz
Already downloaded: /Library/Caches/Homebrew/lsyncd-2.1.5.tar.gz
Error: Formula  does not define resource "xnu".
</pre>