merges r21783 from trunk into ruby_1_9_1.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@21838 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merges r21783 from trunk into ruby_1_9_1.
ruby.h and defines.h. [ruby-core:21570]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@21838 b2dd03c8-39d4-4d8f-98ff-823fe69b080e