qapi: Add 'if' to implicit struct members

The generated code is for now *unconditional*.  Later patches generate
the conditionals.

Note that union discriminators may not have 'if' conditionals.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20181213123724.4866-14-marcandre.lureau@redhat.com>
Message-Id: <20181213123724.4866-15-marcandre.lureau@redhat.com>
[Patches squashed, commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
diff --git a/tests/qapi-schema/test-qapi.py b/tests/qapi-schema/test-qapi.py
index aadf252..27081cb 100644
--- a/tests/qapi-schema/test-qapi.py
+++ b/tests/qapi-schema/test-qapi.py
@@ -39,6 +39,7 @@
         for m in members:
             print('    member %s: %s optional=%s'
                   % (m.name, m.type.name, m.optional))
+            self._print_if(m.ifcond, 8)
         self._print_variants(variants)
         self._print_if(ifcond)