libxl: libxl_domain_create_restore has an extra argument

libxl: libxl_domain_create_restore has an extra argument

In the latest libxenlight code, libxl_domain_create_restore accepts a
new argument. Update libvirt's libxl driver for that. Use the macro
provided by libxenlight to detect which version should be used.

The new parameter (send_back_fd) is set to -1 because libvirt provides
no such fd.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Message-id: 1459866012-27081-1-git-send-email-wei.liu2@citrix.com
(cherry picked from commit 216650f14b35ad11a45505405347f8027bc294d7)