awful.tag.delete: Deactivate tags

The activated property was added to tag objects between awesome 3.4 and 3.5.
This is used in the C code to keep tags alive even when nothing else refers to
it and includes a tag e.g. in some root window properties.

Thus, to get rid of a tag and to make the C code drop its reference to it, we
have to set activated to false in this function.

Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/awful/tag.lua.in

@@ -154,6 +154,7 @@ function tag.delete(target_tag, fallback_tag)
 
     -- delete the tag
     data.tags[target_tag].screen = nil
+    target_tag.activated = false
 
     -- If no tags are visible, try and view one.
     if tag.selected(target_scr) == nil and ntags > 0 then