qapi transaction: Elide redundant has_FOO in generated C

The has_FOO for pointer-valued FOO are redundant, except for arrays.
They are also a nuisance to work with.  Recent commit "qapi: Start to
elide redundant has_FOO in generated C" provided the means to elide
them step by step.  This is the step for qapi/transaction.json.

Said commit explains the transformation in more detail.  The invariant
violations mentioned there do not occur here.

In qmp_transaction(), we can't just drop parameter @has_props, since
it's used to track whether @props needs to be freed.  Replace it by a
local variable.

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Hanna Reitz <hreitz@redhat.com>
Cc: qemu-block@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221104160712.3005652-27-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

blockdev.c

@@ -1048,7 +1048,7 @@ static void blockdev_do_action(TransactionAction *action, Error **errp)
 
     list.value = action;
     list.next = NULL;
-    qmp_transaction(&list, false, NULL, errp);
+    qmp_transaction(&list, NULL, errp);
 }
 
 void qmp_blockdev_snapshot_sync(const char *device, const char *node_name,
@@ -2289,11 +2289,11 @@ static TransactionProperties *get_transaction_properties(
  * Always run under BQL.
  */
 void qmp_transaction(TransactionActionList *dev_list,
-                     bool has_props,
                      struct TransactionProperties *props,
                      Error **errp)
 {
     TransactionActionList *dev_entry = dev_list;
+    bool has_props = !!props;
     JobTxn *block_job_txn = NULL;
     BlkActionState *state, *next;
     Error *local_err = NULL;

scripts/qapi/schema.py

@@ -759,7 +759,6 @@ def need_has(self):
         assert self.type
         # Temporary hack to support dropping the has_FOO in reviewable chunks
         opt_out = [
-            'qapi/transaction.json',
             'qapi/ui.json',
             'qapi/virtio.json',
             'qga/qapi-schema.json']