Fix some hook ordering problems. mod_vhost_alias should, perhaps, be HOOK_LAST.

It redefines the document root, so it should only be used if no other mapper wants
the request.  I haven't made that change here; I've simply put explict ordering
to make sure we get

mod_alias -> mod_userdir -> mod_vhost_alias

I can't compile apache at the moment for other reasons, so this is untested,
but it looks right to me.

PR: 8853


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96137 13f79535-47bb-0310-9956-ffa450edef68