Implement new ScoreBoardFile directive logic. This affects how we

Implement new ScoreBoardFile directive logic. This affects how we
create the scoreboard's shared memory segment. We now have the best of
both worlds:

if config specifies ScoreBoardFile
  create name-based shared memory, errors are fatal
else /* we get to choose */
  create anonymous shared memory
  if ENOTIMPL
    create name-based shared memory from DEFAULT_SCOREBOARD
  else
    errors are fatal

This gives us the flexibility to have anonymous shared memory (on platforms
that support it) as well as name-based shared memory when third-party
programs want access to our scoreboard.

The ap_scoreboard_fname static variable is now owned by the scoreboard.c
file, and no longer by the MPMs. The MPMs MUST NOT set ap_scoreboard_fname
to a default, since that will override the default creation logic and
only allow name-based segments.

Submitted by:	Aaron Bannert
Reviewed by:	Justin Erenkrantz

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@93434 13f79535-47bb-0310-9956-ffa450edef68