backport the following change from 2.1:

    Enable coredumps on Linux 2.4+ if CoreDumpDirectory is coded

I tried to clarify the doc, but it still looks like geek-speak.  Any ideas
on how to better explain this to users would be appreciated.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/APACHE_2_0_BRANCH@99856 13f79535-47bb-0310-9956-ffa450edef68