Properly note lists in other lists as used

If a list:

- list: foo
  items: [a, b, c]

Was referenced in another list:

- list: bar
  items: [foo, d, e, f]

The first list would not be marked as used, when it should.

This avoids mistaken messages like "list xxx not refered to by any rule/macro/list"

Signed-off-by: Mark Stemm <mark.stemm@gmail.com>

userspace/engine/lua/rule_loader.lua

@@ -861,6 +861,7 @@ function load_rules(sinsp_lua_parser,
 	 if (state.lists[item] == nil) then
 	    items[#items+1] = quote_item(item)
 	 else
+	    state.lists[item].used = true
 	    for i, exp_item in ipairs(state.lists[item].items) do
 	       items[#items+1] = exp_item
 	    end