Update snippets

codegen/dbl_list/snippets/list_pop_back

@@ -12,7 +12,7 @@
   }}
 
   --(list->node_count);
-  list->last        = output->prev;
+  list->last = output->prev;
 
   output->prev = output->next = NULL;
 

codegen/dbl_list/snippets/list_pop_front

@@ -12,7 +12,7 @@
   }}
 
   --(list->node_count);
-  list->first       = output->next;
+  list->first = output->next;
 
   output->prev = output->next = NULL;