* server/core.c: Add new directive: 'AcceptFilter'.

* server/core.c: Enable 'httpready' by default on systems that support it.  Use dataready filters for others.
* server/listen.c: Move bits that determined which accept filter is applied to core.c.
* server/listen.c: Add bits to find the correct accept filter based on the core's configuration.
* include/http_core.h: Add the accf_map table to the core_server_config structure

Tested on Linux using TCP_DEFER_ACCEPT. 
Needs testing on FreeBSD to make sure that Accept Filters actually work.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/listen-protocol@171031 13f79535-47bb-0310-9956-ffa450edef68