[libvirt] Initial working Mac OS X libvirt client build

[Justin Clift]

Hi all,

This is for anyone using the Homebrew package management system on Mac 
OS X. :)

A first working (but still experimental) libvirt formula is online:

   http://github.com/justinclift/libvirt

It includes the libvirt text mode client (virsh), and the libvirt 
development libraries.

If you have time to test it and report success/failure/(etc), please do.

Be aware, for the moment, it pulls down a tarred up snapshot of libvirt 
git, with a few trivial patches applied to make compiling work:

What works:

   + Remote connections using TLS (qemu+tls://)  <-- encrypted
   + Remote connections using TCP (qemu+tls://)  <-- not encrypted!

What doesn't work:

   + Remote connections using SSH (qemu+ssh://), if the server has
     PolicyKit enabled. (possible bug, will look into it)

     In theory, this means connecting to Ubuntu server should work,
     as that uses groups to control access rather than PolicyKit.
     Haven't tried it though, so if you do, please let me know how
     it goes. ;)

Testing and feedback is encouraged.  The aim here is to have the libvirt 
client (virsh) plus development libraries work properly on OS X.

Please note, I'm new to OS X, github, and Homebrew, so if you notice 
things that should be done better/differently/etc, please let me know. :)

Regards and best wishes,

Justin Clift