testcase.rb: call super

* test/lib/test/unit/testcase.rb (method_added): hook methods
  should call super.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49134 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/lib/test/unit/testcase.rb

@@ -22,6 +22,7 @@ module Test
       end
 
       def self.method_added(name)
+        super
         return unless name.to_s.start_with?("test_")
         @test_methods ||= {}
         if @test_methods[name]