* ext/openssl/extconf.rb: check SSL_CTX_set_next_proto_select_cb
	  function rather than OPENSSL_NPN_NEGOTIATED macro. it exists
	  even if it is disabled by OpenSSL configuration.
	  [ruby-core:74384] [Bug #12182]

	* ext/openssl/ossl_ssl.c: update #ifdef(s) as above.

	* test/openssl/test_ssl.rb: skip NPN tests if NPN is disabled.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@54551 b2dd03c8-39d4-4d8f-98ff-823fe69b080e