Use percents chars for delimiters, because the chance is higher that a colon

is inside some of the flags than a percent char. (GNU Autoconf does the same
when substituting flags)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@81016 13f79535-47bb-0310-9956-ffa450edef68