Bring xapi-project/xcp-eliloader up to date with mcclurmc/xcp-eliloader (its grandparent)

xapi-project/xcp-eliloader was forked from jonludlam/xcp-eliloader, which was forked from mcclurmc/xcp-eliloader.   mcclurmc/xcp-eliloader has lots of changes which never made it into xapi-project/xcp-eliloader.   xenserver-core uses djs55/xcp-eliloader, which was forked from mcclurmc/xcp-eliloader and has a couple more patches.

This pull request brings xapi-project/xcp-eliloader up to date with mcclurmc/xcp-eliloader.   Once it is applied I'll send another pull request to incorporate the further changes in djs55/xcp-eliloader.