qapi: fix flat union on uncovered branches conditionals

Default branches variant should use the member conditional.

This fixes compilation with --disable-replication.

Fixes: 335d10cd8e2c3bb6067804b095aaf6371fc1983e

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20181217204046.14861-1-marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Long line wrapped]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

scripts/qapi/common.py

@@ -1460,7 +1460,8 @@ def check(self, schema, seen):
             cases = set([v.name for v in self.variants])
             for m in self.tag_member.type.members:
                 if m.name not in cases:
-                    v = QAPISchemaObjectTypeVariant(m.name, 'q_empty')
+                    v = QAPISchemaObjectTypeVariant(m.name, 'q_empty',
+                                                    m.ifcond)
                     v.set_owner(self.tag_member.owner)
                     self.variants.append(v)
         for v in self.variants: