an instance variable "private" is added to OpenSSL::PKey class.
  this ivar is a flag that shows whether there is a private key
  in the instance.

* ext/openssl/ossl_engine.c: (ossl_engine_load_privkey): set private
  key flag.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@9218 b2dd03c8-39d4-4d8f-98ff-823fe69b080e