Merge r1818726 from trunk:

mod_proxy: allow SSLProxyCheckPeer* usage for all proxy modules.

PR 61857.

Proposed by: Markus Gausling <markusgausling googlemail.com>
Reviewed by: ylavic, rjung, rpluem


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1859844 13f79535-47bb-0310-9956-ffa450edef68