allow two character mod_log_config formats



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1610686 13f79535-47bb-0310-9956-ffa450edef68
Suggestion from Rick Houser -- for compatibility, pick an unusual
character as the first character in a 2/3 character pattern.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1610707 13f79535-47bb-0310-9956-ffa450edef68