revert error attributes
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55131 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
revert error attributes
which may not be optimized away in readline extension library.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55131 b2dd03c8-39d4-4d8f-98ff-823fe69b080e