tools/ocaml: Build fix following libxl API changes
The following libxl API became asynchronous and gained an additional
`ao_how' parameter:
libxl_domain_pause()
libxl_domain_unpause()
libxl_send_trigger()
Adapt the ocaml binding.
Build tested only.
Fixes: edaa631ddcee665cdfae1cf6bc7492c791e01ef4 Fixes: 95627b87c3159928458ee586e8c5c593bdd248d8 Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>