ivar name typo in a Tk sample

* ext/tk/sample/tktextio.rb: @opne => @open

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53340 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/tk/sample/tktextio.rb

@@ -421,7 +421,7 @@ class TkTextIO < TkText
     nil
   end
   def close_write
-    @open[:w] = false if @opne[:w]
+    @open[:w] = false if @open[:w]
     nil
   end