Partial port of proposed r1773158 for httpd-2.x only; this change causes all

Partial port of proposed r1773158 for httpd-2.x only; this change causes all
illegible protocol args to be rejected, irrespective of the strict toggle as
we expect this to occur with a garbage raw SP embedded in the request URI.

Simplifies the code using the protocol 0.9 sentinal to set up an http/1.0
error response.

String duplication of r1773158 is uninteresting, httpd-2.x has a const protocol
member.

Submitted by: rpluem, wrowe

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1773159 13f79535-47bb-0310-9956-ffa450edef68