forwardable.rb: fix branches

* lib/forwardable.rb (instance_delegate, single_delegate): fix
  inverted branches.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57257 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/forwardable.rb

@@ -131,7 +131,7 @@ module Forwardable
   #
   def instance_delegate(hash)
     hash.each do |methods, accessor|
-      if defined?(methods.each)
+      unless defined?(methods.each)
         def_instance_delegator(accessor, methods)
       else
         methods.each {|method| def_instance_delegator(accessor, method)}
@@ -263,7 +263,7 @@ module SingleForwardable
   #
   def single_delegate(hash)
     hash.each do |methods, accessor|
-      if defined?(methods.each)
+      unless defined?(methods.each)
         def_single_delegator(accessor, methods)
       else
         methods.each {|method| def_single_delegator(accessor, method)}