s3-dcerpc: Break memory hierarchy for shared structure

Handles are shared among multiple pipes_struct. We cannot allocate
them on any specific pipes_struct or it will vanish for all others
as soon as that pipes_struct is freed, leaving back dangling
pointers.

source3/rpc_server/rpc_handles.c

@@ -103,7 +103,7 @@ bool init_pipe_handles(pipes_struct *p, const struct ndr_syntax_id *syntax)
 		/*
 		 * First open, we have to create the handle list
 		 */
-		hl = talloc_zero(p, struct handle_list);
+		hl = talloc_zero(NULL, struct handle_list);
 		if (hl == NULL) {
 			return false;
 		}