[ruby/delegate] test: remove needless mu_pp

It's for minitest. We don't need it with test-unit.

ruby/delegate@447cd43973

test/test_delegate.rb

@@ -3,14 +3,6 @@
 require 'delegate'
 
 class TestDelegateClass < Test::Unit::TestCase
-  module PP
-    def mu_pp(obj)
-      str = super
-      str = "#<#{obj.class}: #{str}>" if Delegator === obj
-      str
-    end
-  end
-
   module M
     attr_reader :m
   end
@@ -215,7 +207,6 @@ def s.bar; end
   end
 
   def test_eql?
-    extend PP
     s0 = SimpleDelegator.new("foo")
     s1 = SimpleDelegator.new("bar")
     s2 = SimpleDelegator.new("foo")