Whitespace: Xapi_hooks.internal_host_dead_hook

$ camlp4o -printer o -no_comments ocaml/xapi/xapi_hooks.ml | md5sum
40447b4d2bbed13c5f1b97214766a41a  -
$ git checkout HEAD^
$ camlp4o -printer o -no_comments ocaml/xapi/xapi_hooks.ml | md5sum
40447b4d2bbed13c5f1b97214766a41a  -

Signed-off-by: John Else <john.else@citrix.com>
CA-151605: Fix race in host_dead_hook

If any tasks are destroyed or GCed after getting the list of tasks but
before finding the host to which they were forwarded, the
host_post_declare_dead hook script will not actually be called.

Signed-off-by: John Else <john.else@citrix.com>