libxl: Deprecate libxl__domain_{unpause,resume}

libxl: Deprecate libxl__domain_{unpause,resume}

These two functions are used from many places in libxl and need to
change to be able to accomodate libxl__ev_qmp calls and thus needs to
be asynchronous.

(There is also libxl__domain_resume_device_model in the mix.)

A later patch will introduce a new libxl__domain_resume and
libxl__domain_unpause which will make use of libxl__ev_qmp.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>