system: only show crash reports to admins

We could check admin or page access rights, but in the end we just
want to avoid showing a banner that links to a page that is not
accessible in 99% of the cases if specific dashboard access was
granted.

src/www/guiconfig.inc

@@ -473,6 +473,10 @@ date_default_timezone_set($timezone);
 
 function get_crash_report($pedantic = false)
 {
+    if (!userIsAdmin($_SESSION['Username'])) {
+        return;
+    }
+
     $savemsg = sprintf(
         gettext('A problem was detected. Click %shere%s for more information.'),
         '<a href="/crash_reporter.php">',

src/www/index.php

@@ -332,7 +332,7 @@ include("fbegin.inc");?>
 <?php
           print_service_banner('livecd');
           $crash_report = get_crash_report();
-          if ($crash_report != '') {
+          if (!empty($crash_report)) {
               print_info_box($crash_report);
           }?>
         </div>