Add ap_append_pid(); This is performed enough to warrant

a function I think, especially with the fact that
the mapping of getpid() to APR_PID_T_FMT isn't
consistant in some areas. 


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@265506 13f79535-47bb-0310-9956-ffa450edef68