Silence ulimit warnings on platforms/configs that don't support setting the

soft limit to the hard limit (aka default Mac OS X).

* support/config.m4: Redirect output to /dev/null.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@730911 13f79535-47bb-0310-9956-ffa450edef68