src: fix bad sizeof expression

It was computing the size of the pointer, not the size of the pointed-to
object.

Introduced in commit 727b291 ("src,dns: refactor cares_wrap to avoid
global state".)

PR-URL: #17014
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Daniel Bevenius <[email protected]>
Reviewed-By: Franziska Hinkelmann <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>

src/cares_wrap.cc

@@ -160,7 +160,7 @@ class ChannelWrap : public AsyncWrap {
   }
   inline node_ares_task_list* task_list() { return &task_list_; }
 
-  size_t self_size() const override { return sizeof(this); }
+  size_t self_size() const override { return sizeof(*this); }
 
   static void AresTimeout(uv_timer_t* handle);