Using "deltask" assumes that do_rm_work has been added already, which
won't be the case anymore in the upcoming improved rm_work.bbclass,
because then an anonymous python method will add do_rm_work.
Setting RM_WORK_EXCLUDE works with the current and upcoming
rm_work.bbclass and is the API that is meant to be used for excluding
recipes from cleaning, so use that.
Signed-off-by: Patrick Ohly <patrick.ohly@intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
