[Change] Render spfx in reverse order.

src/spfx.c

@@ -297,7 +297,7 @@ void spfx_render(const int layer) {
   }
 
   /* Now render the layer. */
-  for(i = 0; i < spfx_nstack; i++) {
+  for(i = spfx_nstack-1; i >= 0; i--) {
     effect = &spfx_effects[spfx_stack[i].effect];
 
     /* Simplifies. */