tests/qapi-schema: Tweak to demonstrate buggy member name check

Member name 'u' and names starting with 'has-' or 'has_' are reserved
for the generator.  check_type() enforces this, covered by tests
reserved-member-u and reserved-member-has.

These tests neglect to cover optional members, where the name starts
with '*'.  Tweak reserved-member-u to fix that.  Test
reserved-member-has still covers non-optional members.

This demonstrates the reserved member name check is broken for
optional members.  The next commit will fix it.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210323094025.3569441-7-armbru@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
[Commit message improved slightly]

tests/qapi-schema/reserved-member-u.err

@@ -1,2 +0,0 @@
-reserved-member-u.json: In struct 'Oops':
-reserved-member-u.json:7: 'data' member 'u' uses reserved name

tests/qapi-schema/reserved-member-u.json

@@ -4,4 +4,5 @@
 # This is true even for non-unions, because it is possible to convert a
 # struct to flat union while remaining backwards compatible in QMP.
 # TODO - we could munge the member name to 'q_u' to avoid the collision
-{ 'struct': 'Oops', 'data': { 'u': 'str' } }
+# BUG: not rejected
+{ 'struct': 'Oops', 'data': { '*u': 'str' } }

tests/qapi-schema/reserved-member-u.out

@@ -0,0 +1,14 @@
+module ./builtin
+object q_empty
+enum QType
+    prefix QTYPE
+    member none
+    member qnull
+    member qnum
+    member qstring
+    member qdict
+    member qlist
+    member qbool
+module reserved-member-u.json
+object Oops
+    member u: str optional=True