qapi2texi: Don't hide undocumented members and arguments

qapi2texi: Don't hide undocumented members and arguments

Show undocumented object, alternate type members and command, event
arguments exactly like undocumented enumeration type values.

Example change (qemu-qmp-ref.txt):

  -- Command: query-rocker

      Return rocker switch information.

+     Arguments:
+     'name'
+          Not documented
+
      Returns: 'Rocker' information

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1489582656-31133-24-git-send-email-armbru@redhat.com>