perf report: Use map_symbol__copy() when copying callchains

It seems there are places to miss updating refcount of maps.
Let's use map_symbol__copy() helper to properly copy them with
refcounts updated.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/util/callchain.c

···
 			return -ENOMEM;
 		}
 		call->ip = cursor_node->ip;
-		call->ms = cursor_node->ms;
-		call->ms.map = map__get(call->ms.map);
-		call->ms.maps = maps__get(call->ms.maps);
+		map_symbol__copy(&call->ms, &cursor_node->ms);
 		call->srcline = cursor_node->srcline;
 
 		if (cursor_node->branch) {
···
 
 	node->ip = ip;
 	map_symbol__exit(&node->ms);
-	node->ms = *ms;
-	node->ms.maps = maps__get(ms->maps);
-	node->ms.map = map__get(ms->map);
+	map_symbol__copy(&node->ms, ms);
 	node->branch = branch;
 	node->nr_loop_iter = nr_loop_iter;
 	node->iter_cycles = iter_cycles;
···
 				goto out;
 			*new = *chain;
 			new->has_children = false;
-			new->ms.map = map__get(new->ms.map);
+			map_symbol__copy(&new->ms, &chain->ms);
 			list_add_tail(&new->list, &head);
 		}
 		parent = parent->parent;