Use generic whitespace character class when parsing

"require" directives, instead of literal spaces only.

PR: 17135
Reviewed by: Jeff Trawick, Bill Stoddard


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@99808 13f79535-47bb-0310-9956-ffa450edef68