CA-159588: use synchronous libxl domain destroy rather than async
CA-159588: use synchronous libxl domain destroy rather than async

The async version was failing part of the way through with a timeout,
after killing the qemu but before killing the domain.

The synchronous version seems to work ok.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@eu.citrix.com>

thomassa/xenopsd,koushikcgit/xenopsd,koushikcgit/xenopsd,euanh/xenopsd,thomassa/xenopsd,johnelse/xenopsd,djs55/xenopsd,johnelse/xenopsd,thomassa/xenopsd,euanh/xenopsd,koushikcgit/xenopsd,euanh/xenopsd,johnelse/xenopsd,djs55/xenopsd,djs55/xenopsd