Fix patchset level comment link

When fixing .soy files, it necessary to fix both X.soy and XHtml.soy
This adds to the fix of I45371156.

Bug: Issue 12997
Change-Id: I91e33e1cc9f11b868676a3ba5c1a9ba041e3a59c
diff --git a/resources/com/google/gerrit/server/mail/Comment.soy b/resources/com/google/gerrit/server/mail/Comment.soy
index 1eb016b..fc92b31 100644
--- a/resources/com/google/gerrit/server/mail/Comment.soy
+++ b/resources/com/google/gerrit/server/mail/Comment.soy
@@ -41,7 +41,7 @@
   {for $group in $commentFiles}
     // Insert a space before the newline so that Gmail does not mistakenly link
     // the following line with the file link. See issue 9201.
-    {$group.link}{sp}{\n}
+    {if $group.link}{$group.link}{sp}{/if}{\n}
     {$group.title}:{\n}
     {\n}