Prohibit SystemStackError while GC.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59089 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Prohibit SystemStackError while GC.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59089 b2dd03c8-39d4-4d8f-98ff-823fe69b080e