test_ocsp.rb: run separately

* test/openssl/test_ocsp.rb (test_new_ocsp_request): run in a
  separated process to continue on CentOS 5.6 i386.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48819 b2dd03c8-39d4-4d8f-98ff-823fe69b080e