Updated changelog with the last change of mod_proxy_fcgi

r1759984, r1760018 and r1752347 are all changes related
to a bug fixed for mod_proxy_fcgi.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1769593 13f79535-47bb-0310-9956-ffa450edef68