something amiss in 2.4.x

[Stefan Eissing]

In my h2 test suite, I get on the 2.4.x branch a no longer working propxy setup.

error_log shows
[Wed Feb 14 17:11:35.996712 2018] [proxy:warn] [pid 69638:tid 123145425334272] 
[client 127.0.0.1:50616] AH01144: No protocol handler was valid for the URL 
/proxy/index.html (scheme 'balancer'). If you are using a DSO version of 
mod_proxy, make sure the proxy submodules are included in the configuration 
using LoadModule.

Same setup works flawlessly on trunk.

config basically is

    <Proxy "balancer://http-local">
        BalancerMember "http://127.0.0.1:12345"; hcmethod=GET hcuri=/
    </Proxy>

    <VirtualHost...>

      ProxyPass "/proxy" "balancer://http-local"
      ProxyPassReverse "/proxy" "balancer://http-local"
    </VirtualHost>

Compiled clean several times already. Did we miss something on the backport?

-Stefan