package/libvirt: new package

Libvirt is collection of software that provides a convenient way to
manage virtual machines and other virtualization functionality, such as
storage and network interface management. These software pieces include
an API library, a daemon (libvirtd), and a command line utility (virsh).

   http://libvirt.org/



Signed-off-by: Jared Bents <jared.bents@rockwellcollins.com>
[Arnout:
 - Re-introduce BR2_PACKAGE_LIBVIRT_ARCH_SUPPORTS
 - Put all Config.in comments on one line
 - Put the comment before the option itself (makes sure sub-option
   indention is good)
 - Remove spurious BR2_PACKAGE_NETCAT dependency
 - Alphabetically order dependencies in Config.in
 - Add select of libglib2
 - Alphabetically order CONF_OPTS
]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>