json_elements: json_return_type: move-assignment operator: detect self-move
json_elements: json_return_type: move-assignment operator: detect self-move

Move members only when not assigning self onto self.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

avikivity/seastar,syuu1228/seastar,avikivity/seastar,scylladb/seastar,scylladb/seastar,avikivity/seastar,scylladb/seastar,syuu1228/seastar,syuu1228/seastar