Merge r1859371, r1859422 from trunk:

Merge r1859371, r1859422 from trunk:

mod_proxy/ssl: Proxy SSL client certificate
configuration and other proxy SSL configurations
broken inside <Proxy> context.
PR 63430
Triggered by r1855646+r1855748.
Patch from rpluem (proxy) and ylavic (ssl).

Follow up to r1859371: extend to other ap_proxy_connection_create[_ex]() users.

This function now now handles SSL reuse as well as the "proxy-request-hostname"
note (SNI), so let's also call it unconditionnaly in all proxy modules.

On the mod_ssl side, since this note has the lifetime of the connection, don't
reset/unset it during handshake (ssl_io_filter_handshake).

Submitted by: rjung, ylavic
Reviewed by: rjung, rpluem, ylavic

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1859845 13f79535-47bb-0310-9956-ffa450edef68