sdl12-compat: SDL does support 1 and 4 bit surfaces, so allow these depths

SDL Commits
1 
From 1c6b5baf3923e5afcd115e00273d9d7ffcb22956 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Thu, 17 Nov 2022 01:11:24 -0800
Subject: [PATCH] SDL does support 1 and 4 bit surfaces, so allow these depths

1-bit bitmap surfaces are used by Maelstrom for rendering text, for example

Fixes https://github.com/libsdl-org/sdl12-compat/issues/274
---
 src/SDL12_compat.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 1123cc91f..6964e2b7d 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -4992,16 +4992,16 @@ SDL_CreateRGBSurface(Uint32 flags12, int width, int height, int depth, Uint32 Rm
     }
 
     /* !!! FIXME: this isn't strictly correct, but SDL2 doesn't support
-       !!! FIXME:  surfaces smaller than 8 bits, and this lets at
-       !!! FIXME:  least one game function correctly. */
-    if (depth < 8) {
+       !!! FIXME: arbitrary depths smaller than 8 bits, and this lets at
+       !!! FIXME:  least one game (rockdodger) function correctly. */
+    if (depth < 8 && depth != 1 && depth != 4) {
         if (WantDebugLogging) {
             SDL20_Log("This app is creating an %d-bit SDL_Surface, but we are bumping it to 8-bits. If you see rendering issues, please report them!", depth);
         }
         depth = 8;
     }
 
-    if (depth == 8) {  /* don't pass masks to SDL2 for 8-bit surfaces, it'll cause problems. */
+    if (depth <= 8) {  /* don't pass masks to SDL2 for <= 8-bit surfaces, it'll cause problems. */
         surface20 = SDL20_CreateRGBSurface(0, width, height, depth, 0, 0, 0, 0);
     } else {
         surface20 = SDL20_CreateRGBSurface(0, width, height, depth, Rmask, Gmask, Bmask, Amask);