download page donation tracking

Signed-off-by: Christopher Guindon <chris.guindon@eclipse-foundation.org>
diff --git a/content/en_index.php b/content/en_index.php
index f3affc7..81ad678 100644
--- a/content/en_index.php
+++ b/content/en_index.php
@@ -23,7 +23,9 @@
   <?php
   // Infra 2193 - The container-thankyou div is needed for the Successful
   // Downloads page.
+  $is_download_page = FALSE;
   if (isset($title_1) && isset($title_2) && isset($download_link)) :
+    $is_download_page = TRUE;
     ?>
     <div class="container-thankyou">
       <div class="row thankyou text-center">
@@ -143,6 +145,9 @@
           > <input type="hidden" name="credit_process_url"
             value="<?php print $Paypal->get_gateway_credit_process_url();?>"
           > <input type="submit" value="Donate" class="btn btn-warning">
+          <?php if ($is_download_page) :?>
+            <input type="hidden" name="landing_page" value="download">
+          <?php endif;?>
         </div>
       </form>
     </div>