Correct perl version check in APR::PerlIO::PERLIO_LAYERS_ARE_ENABLED().
Sadly this was not the cause of t/apache/subprocess.t failing on Windows with httpd-2.4.x.

git-svn-id: https://svn.apache.org/repos/asf/perl/modperl/branches/httpd24threading@1565129 13f79535-47bb-0310-9956-ffa450edef68