Fix for httpd-test modules/include test #17.

Fix for httpd-test modules/include test #17.

If we are *already* a faux URI (i.e. relative file sub req) and we then
make a subrequest from that faux URI to a file in the same directory,
we'd try to build a URI out of the fake URI which leads to the wrong
thing happening somewhere down the line.  So, let's just give this
special case a fake URI as well.

OtherBill needs to verify this.  He can back it out if he wants.  I
don't much care.  It's one line and it seems okay...

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91187 13f79535-47bb-0310-9956-ffa450edef68