authn_provider_alias adds the configuration block tag

<AuthnProviderAlias baseProvider Alias>
Authentication directives contained within this block can be
referenced as a new authProvider using the AuthBasicProvider or
AuthDigestProvider directives.  These directives will be merged in to
the per_dir configuration just before the base provider is called.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@177985 13f79535-47bb-0310-9956-ffa450edef68