12166 resync smatch to 0.6.1-rc1-il-3

@@ -1093,10 +1093,19 @@
 {
         struct stree *stree;
         struct stree *implied_stree;
 
         stree = pop_stree(&switch_stack);
+        if (!stree) {
+                /*
+                 * If the cur_stree was NULL before the start of the switch
+                 * statement then we don't want to unnullify it.
+                 *
+                 */
+                push_stree(&switch_stack, stree);
+                return;
+        }
         implied_stree = __implied_case_stree(switch_expr, case_rl, &remaining_cases, &stree);
         merge_stree(&cur_stree, implied_stree);
         free_stree(&implied_stree);
         push_stree(&switch_stack, stree);
 }