432192 - jetty-start / Allow JETTY_LOGS use for start-log-file

+ Internal initialization & validation of start-log-file is
  done via BaseHome.getPath(String) to allow the path to be
  anywhere on the filesystem, not just under ${jetty.base}

jetty-start/src/main/java/org/eclipse/jetty/start/StartLog.java

@@ -113,7 +113,7 @@ public class StartLog
 
         if (logFileName != null)
         {
-            Path logfile = baseHome.getBasePath(logFileName);
+            Path logfile = baseHome.getPath(logFileName);
             initLogFile(logfile);
         }
     }