core: Follow up to r1902728 and r1902906: simplify for APR-1.8+.

apr_threadattr_max_free_set() is now in APR-1.8.x.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1902909 13f79535-47bb-0310-9956-ffa450edef68
1 file changed