Merge r1779574, r1779623 from trunk:

mod_proxy_hcheck: Don't validate timed out responses.



mod_proxy_hcheck: follow up to r1779574.
Parse/validate response bodies.


Submitted by: ylavic
Reviewed by: ylavic, jim, druggeri


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1789960 13f79535-47bb-0310-9956-ffa450edef68