Do make the code a bit clearer, some minor #define changes (and
the resultant flow-thru in the docs).
SAFE_UNSERIALIZED_ACCEPT -> SINGLE_LISTEN_UNSERIALIZED_ACCEPT
HAVE_MMAP -> USE_MMAP_SCOREBOARD
HAVE_SHMGET -> USE_SHMGET_SCOREBOARD
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@79959 13f79535-47bb-0310-9956-ffa450edef68