Fix: Allow -post-compile-test for SVN to run on Windows

When passing file:// protocol url to svn.exe on Windows, it fails.
Use file:/// prefix, with which both Linux and Windows work fine.

Author: 0xfeeddeadbeef

opengrok-indexer/build.xml

@@ -164,7 +164,7 @@ Copyright (c) 2007, 2017, Oracle and/or its affiliates. All rights reserved.
 
       <!-- need absolute path for svn url -->
       <pathconvert property="test.svn.url">
-        <map from="" to="file://"/>
+        <map from="" to="file:///"/>
         <path location="${build.test.reposroots}/svn"/>
       </pathconvert>