BUG/MINOR: stats: Fix HTML output for the frontends heading

Since the flag STAT_SHOWADMIN was removed, the frontends heading in the HTML
output appears unaligned because the space reserved for the checkbox (not
displayed for frontends) is not inserted.

This patch fixes the issue #390. It must be backported to 2.1.
diff --git a/src/stats.c b/src/stats.c
index 5954fe6..32236f4 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -2020,14 +2020,17 @@
 	              (appctx->ctx.stats.flags & STAT_SHLGNDS) ? "</u>":"",
 	              px->desc ? "desc" : "empty", px->desc ? px->desc : "");
 
-	if ((px->cap & PR_CAP_BE) && px->srv && (appctx->ctx.stats.flags & STAT_ADMIN)) {
+	if (appctx->ctx.stats.flags & STAT_ADMIN) {
 		/* Column heading for Enable or Disable server */
-        chunk_appendf(&trash,
-                "<th rowspan=2 width=1><input type=\"checkbox\" \
-                onclick=\"for(c in document.getElementsByClassName('%s-checkbox')) \
-                document.getElementsByClassName('%s-checkbox').item(c).checked = this.checked\"></th>",
-                px->id,
-                px->id);
+		if ((px->cap & PR_CAP_BE) && px->srv)
+			chunk_appendf(&trash,
+				      "<th rowspan=2 width=1><input type=\"checkbox\" "
+				      "onclick=\"for(c in document.getElementsByClassName('%s-checkbox')) "
+				      "document.getElementsByClassName('%s-checkbox').item(c).checked = this.checked\"></th>",
+				      px->id,
+				      px->id);
+		else
+			chunk_appendf(&trash, "<th rowspan=2></th>");
 	}
 
 	chunk_appendf(&trash,