Merge of r1426802,1744460,1829799,1824716,1838318,1840678,1861294

Merge of r1426802,1744460,1829799,1824716,1838318,1840678,1861294

  *) easy patches to synch 2.4.x and trunk:
        - core: extend description of r->hostname
        - mod_proxy_http: Avoid memory allocation before making sure that this handler can handle the URL
        - core: Save a few cycles in 'ap_parse_form_data()'
        - mod_cache_socache: Save some cycles
        - mod_proxy_ftp: Save some cycle
        - vhost: move an assignment to the end of the loop to ease readability and please a compiler
        - core: Be a little more verbose when an error in trigerred in 'ap_set_file_slot()'

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1863316 13f79535-47bb-0310-9956-ffa450edef68