Define enum types for Unicode enums

We want to stop shipping PangoScript in pango, so
we need a replacement for the type that used to
be provided by pango.

docs/reference/gobject/meson.build

@@ -6,7 +6,8 @@ if get_option('gtk_doc')
     'gatomicarray.h',
     'gobject_probes.h',
     'gobject_trace.h',
-    'gtype-private.h'
+    'gtype-private.h',
+    'gobjectenumtypes.h'
   ]
 
   ignore_decorators = [