Import QEMU upstream snapshot d2e570c

Upstream: https://gitlab.com/qemu-project/qemu.git

Upstream-Commit: d2e570cc0f97b936902a5b1b86b73c0f5998b475

tests/qapi-schema/union-unknown.json

@@ -0,0 +1,6 @@
+# we reject a union with unknown type in branch
+{ 'enum': 'Enum', 'data': [ 'unknown' ] }
+{ 'union': 'Union',
+  'base': { 'type': 'Enum' },
+  'discriminator': 'type',
+  'data': { 'unknown': 'MissingType' } }