_REENTRANT, _THREAD_SAFE, etc., which affect how errno is defined
on some architectures
* ext/openssl/ossl.h: include errno.h after ruby.h
* include/ruby/io.h: include errno.h after ruby/config.h
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65906 b2dd03c8-39d4-4d8f-98ff-823fe69b080e