Add a new directive: MaxMemFree. MaxMemFree makes it possible

to configure the maximum amount of memory the allocators will
hold on to for reuse.  Anything over the MaxMemFree threshold
will be free()d.  This directive is usefull when uncommon large
peaks occur in memory usage.  It should _not_ be used to mask
defective modules' memory use.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95954 13f79535-47bb-0310-9956-ffa450edef68