posts: fixup N+1 query issue in 57dc0cbec.

Using `uploader` triggered extra SQL queries to load the uploader of
every post on the post index page.

app/models/post.rb

@@ -1584,7 +1584,7 @@ class Post < ApplicationRecord
 
   def levelblocked?(user = CurrentUser.user)
     #!user.is_gold? && RESTRICTED_TAGS.any? { |tag| has_tag?(tag) }
-    user != uploader && !user.is_gold? && tag_string.match?(RESTRICTED_TAGS_REGEX)
+    user.id != uploader_id && !user.is_gold? && tag_string.match?(RESTRICTED_TAGS_REGEX)
   end
 
   def banblocked?(user = CurrentUser.user)