ensure host xrd is correct, even if installed in subpath

boot.php

@@ -290,7 +290,7 @@ class App {
 
 		if($this->cmd === '.well-known/host-meta') {
 			require_once('include/hostxrd.php');
-			hostxrd($this->hostname);
+			hostxrd($this->get_baseurl());
 			// NOTREACHED
 		}
 

include/hostxrd.php

@@ -1,10 +1,10 @@
 <?php
 
-function hostxrd($hostname) {
+function hostxrd($baseurl) {
 
 	header("Content-type: text/xml");
 	$tpl = file_get_contents('view/xrd_host.tpl');
-	echo str_replace('$domain',$hostname,$tpl);
+	echo str_replace('$domain',$baseurl,$tpl);
 	session_write_close();
 	exit();
 

view/xrd_host.tpl

@@ -4,9 +4,9 @@
  
     <hm:Host>$domain</hm:Host>
  
-    <Link rel='lrdd' template='http://$domain/xrd/?uri={uri}' />
-    <Link rel='acct-mgmt' href='http://$domain/amcd' />
-    <Link rel='http://services.mozilla.com/amcd/0.1' href='http://$domain/amcd' />
+    <Link rel='lrdd' template='$domain/xrd/?uri={uri}' />
+    <Link rel='acct-mgmt' href='$domain/amcd' />
+    <Link rel='http://services.mozilla.com/amcd/0.1' href='$domain/amcd' />
 	<Link rel="http://oexchange.org/spec/0.8/rel/resident-target" type="application/xrd+xml" 
-		href="http://$domain/oexchange/xrd" />
+		href="$domain/oexchange/xrd" />
 </XRD>