tests/qapi-schema: Prepare for simple union UserDefListUnion removal

Simple unions predate flat unions.  Having both complicates the QAPI
schema language and the QAPI generator.  We haven't been using simple
unions in new code for a long time, because they are less flexible and
somewhat awkward on the wire.

To prepare for their removal, simple union UserDefListUnion has to go.
It is used to cover arrays.  The next few commits will eliminate its
uses, and then it gets deleted.  As a first step, provide struct
ArrayStruct for the tests to be rewritten.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210917143134.412106-12-armbru@redhat.com>

tests/qapi-schema/qapi-schema-test.json

@@ -140,6 +140,22 @@
             'sizes': ['size'],
             'any': ['any'],
             'user': ['Status'] } } # intentional forward ref. to sub-module
+{ 'struct': 'ArrayStruct',
+  'data': { 'integer': ['int'],
+            's8': ['int8'],
+            's16': ['int16'],
+            's32': ['int32'],
+            's64': ['int64'],
+            'u8': ['uint8'],
+            'u16': ['uint16'],
+            'u32': ['uint32'],
+            'u64': ['uint64'],
+            'number': ['number'],
+            'boolean': ['bool'],
+            'string': ['str'],
+            '*sz': ['size'],
+            '*any': ['any'],
+            '*user': ['Status'] } } # intentional forward ref. to sub-module
 
 # for testing sub-modules
 { 'include': 'include/sub-module.json' }

tests/qapi-schema/qapi-schema-test.out

@@ -189,6 +189,22 @@ object UserDefListUnion
     case sizes: q_obj_sizeList-wrapper
     case any: q_obj_anyList-wrapper
     case user: q_obj_StatusList-wrapper
+object ArrayStruct
+    member integer: intList optional=False
+    member s8: int8List optional=False
+    member s16: int16List optional=False
+    member s32: int32List optional=False
+    member s64: int64List optional=False
+    member u8: uint8List optional=False
+    member u16: uint16List optional=False
+    member u32: uint32List optional=False
+    member u64: uint64List optional=False
+    member number: numberList optional=False
+    member boolean: boolList optional=False
+    member string: strList optional=False
+    member sz: sizeList optional=True
+    member any: anyList optional=True
+    member user: StatusList optional=True
 include include/sub-module.json
 command user-def-cmd None -> None
     gen=True success_response=True boxed=False oob=False preconfig=False