Merge r1744206 from trunk:

mod_rewrite: adding h2:// and h2c:// proxy schemes to absolute uri detection, patch by Evgeny Kotkov
Submitted by: icing
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1747056 13f79535-47bb-0310-9956-ffa450edef68