#160603 by nancyw and Freso: variable search_cron_limit was not removed on search uninstall

modules/search/search.install

@@ -18,4 +18,5 @@ function search_uninstall() {
 
   variable_del('minimum_word_size');
   variable_del('overlap_cjk');
+  variable_del('search_cron_limit');
 }