error.c: Exception#cause
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43636 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
error.c: Exception#cause
[Feature #8257]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43636 b2dd03c8-39d4-4d8f-98ff-823fe69b080e