mod_proxy_http: follow up to r1886141, axe overlong scheme check.

mod_proxy_http: follow up to r1886141, axe overlong scheme check.

Since mod_proxy can see CONNECT URIs, "hostname:port" versus "scheme:"
is hardly distinguishable (we don't want to limit the length of hostnames),
and we don't allocate the scheme anymore while parsing, let's simply decline
unrecognized schemes (overlong or not) and be caught by the no-handler case
if there really is no proxy handler interested.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1886151 13f79535-47bb-0310-9956-ffa450edef68