stb_reck_pack: Removed unused assigned variables (under #ifdef _DEBUG wrap)

stb_rect_pack.h

@@ -492,17 +492,14 @@ static stbrp__findresult stbrp__skyline_pack_rectangle(stbrp_context *context, i
    STBRP_ASSERT(cur->next == NULL);
 
    {
-      stbrp_node *L1 = NULL, *L2 = NULL;
       int count=0;
       cur = context->active_head;
       while (cur) {
-         L1 = cur;
          cur = cur->next;
          ++count;
       }
       cur = context->free_head;
       while (cur) {
-         L2 = cur;
          cur = cur->next;
          ++count;
       }