SSLSocket#peer_cert_chain.

* ext/openssl/ossl_x509req.c (GetX509ReqPtr): new function
  which returns underlying X509_REQ.

* ext/openssl/ossl_x509ext.c (ossl_x509extfactory_set_issuer_cert,
  ossl_x509extfactory_set_subject_cert, ossl_x509extfactory_set_crl,
  ossl_x509extfactory_set_subject_req, ossl_x509extfactory_set_config):
  use underlying C struct without duplication not to leak momory.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@4884 b2dd03c8-39d4-4d8f-98ff-823fe69b080e