Fixed garbled characters; ref #5041

mrbgems/mruby-os-memsize/test/memsize.rb

@@ -12,7 +12,7 @@ assert 'ObjectSpace.memsize_of' do
   assert_not_equal ObjectSpace.memsize_of('a'), 0, 'memsize of str'
 
   if __ENCODING__ == "UTF-8"
-    assert_not_equal ObjectSpace.memsize_of("縺薙ｓ縺ｫ縺｡縺ｯ荳也阜"), 0, 'memsize of utf8 str'
+    assert_not_equal ObjectSpace.memsize_of("こんにちは世界"), 0, 'memsize of utf8 str'
   end
 
   # class defs