1.0.0 (30-Jan-2014)
 * only compile the C stubs if the xen headers are present. They
   aren't needed for Mirage kernels.

0.9.9 (30-Jan-2014)
 * replace with the Mirage implementation. This allows the same
   application to be relinked to run in userspace or kernelspace.

0.5.0 (20-Dec-2013)
 * initial release.
