fix unreplaced class var

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3747 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb

@@ -72,7 +72,7 @@ def verify_active_connections!
         end
 
         active_connections.each_value do |connection|
-          connection.verify!(@@connection_cache_timeout)
+          connection.verify!(@@verification_timeout)
         end
       end