qapi: qapi-visit.py, fix list handling for union types

Currently we assume non-list types when generating visitor routines for
union types. This is broken, since values like ['Type'] need to mapped
to 'TypeList'.

We already have a type_name() function to handle this that we use for
generating struct visitors, so use that here as well.

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Amos Kong <akong@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

scripts/qapi-visit.py

@@ -174,7 +174,7 @@ def generate_visit_union(name, members):
 ''',
                 abbrev = de_camel_case(name).upper(),
                 enum = c_fun(de_camel_case(key),False).upper(),
-                c_type=members[key],
+                c_type=type_name(members[key]),
                 c_name=c_fun(key))
 
     ret += mcgen('''