When a test fails to start the daemon print a hint

Failure to start the damon from an acceptance test was not making it
obvious why the test failed. Print a hint to the user suggesting to
look into the error_log for details.

Change-Id: I72a89356f794de1d3d9a706f851db7937b9870ac
Signed-off-by: Sasa Zivkov <sasa.zivkov@sap.com>

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/GerritServer.java

@@ -58,6 +58,8 @@ class GerritServer {
       public Void call() throws Exception {
         int rc = daemon.main(new String[] {"-d", sitePath, "--headless" });
         if (rc != 0) {
+          System.out.println("Failed to start Gerrit daemon. Check "
+              + sitePath + "/logs/error_log");
           serverStarted.reset();
         }
         return null;