Fix compilation on gcc 4.6
if __has_feature is not defined, it can't compile
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43048 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Fix compilation on gcc 4.6
if __has_feature is not defined, it can't compile
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43048 b2dd03c8-39d4-4d8f-98ff-823fe69b080e