rm_work: sort the value of do_build dependencies

This fixes some 'basehash changed' errors when rm_work is being
inherited.

(From OE-Core rev: e74158b6cc1d683ab14ef5d47ec531f986fc2259)

(From OE-Core rev: 8aed35802270345844239406266be37d66ba86c7)

Signed-off-by: Ming Liu <liu.ming50@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/rm_work.bbclass

@@ -164,8 +164,7 @@ python inject_rm_work() {
 
     # Determine what do_build depends upon, without including do_build
     # itself or our own special do_rm_work_all.
-    deps = set(bb.build.preceedtask('do_build', True, d))
-    deps.difference_update(('do_build', 'do_rm_work_all'))
+    deps = sorted((set(bb.build.preceedtask('do_build', True, d))).difference(('do_build', 'do_rm_work_all')) or "")
 
     # deps can be empty if do_build doesn't exist, e.g. *-inital recipes
     if not deps: