engine: Add layout_variant in gensimple.py

Missed to handle layout_variant and also add latam layouts to denylist

BUG=https://github.com/ibus/ibus/issues/2153

engine/denylist.txt

@@ -24,4 +24,5 @@
 # Asterisk(*) character can be used to match any engines.
 # E.g. xkb:cn:*:* excludes xkb:cn::zho and xkb:cn:mon_trad:mvf
 xkb:cn:*:*
+xkb:latam:*:*
 xkb:nec_vndr/jp:*:*

engine/gensimple.py

@@ -180,6 +180,11 @@ class EvdevXML(XMLFilterBase):
             self.__downstream.startElement('layout', AttributesImpl({}))
             self.__downstream.characters(self.__layout)
             self.__downstream.endElement('layout')
+            if self.__variant != '':
+                self.__downstream.startElement('layout_variant',
+                                               AttributesImpl({}))
+                self.__downstream.characters(self.__variant)
+                self.__downstream.endElement('layout_variant')
             self.__downstream.startElement('longname', AttributesImpl({}))
             self.__downstream.characters(self.__description)
             self.__downstream.endElement('longname')