qapi: Drop unused error argument for list and implicit struct

No backend was setting an error when ending the visit of a list or
implicit struct, or when moving to the next list node.  Make the
callers a bit easier to follow by making this a part of the contract,
and removing the errp argument - callers can then unconditionally end
an object as part of cleanup without having to think about whether a
second error is dominated by a first, because there is no second
error.

A later patch will then tackle the larger task of splitting
visit_end_struct(), which can indeed set an error.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1454075341-13658-24-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 7c2148d..2659d3f 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -1,6 +1,7 @@
 /*
  * Dealloc Visitor
  *
+ * Copyright (C) 2012-2016 Red Hat, Inc.
  * Copyright IBM, Corp. 2011
  *
  * Authors:
@@ -84,7 +85,7 @@
     qapi_dealloc_push(qov, obj);
 }
 
-static void qapi_dealloc_end_implicit_struct(Visitor *v, Error **errp)
+static void qapi_dealloc_end_implicit_struct(Visitor *v)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     void **obj = qapi_dealloc_pop(qov);
@@ -99,8 +100,7 @@
     qapi_dealloc_push(qov, NULL);
 }
 
-static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList **listp,
-                                           Error **errp)
+static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList **listp)
 {
     GenericList *list = *listp;
     QapiDeallocVisitor *qov = to_qov(v);
@@ -120,7 +120,7 @@
     return NULL;
 }
 
-static void qapi_dealloc_end_list(Visitor *v, Error **errp)
+static void qapi_dealloc_end_list(Visitor *v)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     void *obj = qapi_dealloc_pop(qov);