sdl12-compat: quirks: Jamestown doesn't work with OpenGL scaling.

SDL Commits
1 
From 1a1944b1e0b1d9f6aa9db70abcb254a92d363409 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Tue, 28 Oct 2025 11:40:27 -0400
Subject: [PATCH] quirks: Jamestown doesn't work with OpenGL scaling.

Fixes #337.
---
 src/SDL12_compat.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 4972cc00f..eea0f685c 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -1454,7 +1454,12 @@ static QuirkEntryType quirks[] = {
 
     /* Loki Unreal Tournament '99 runs at hyperspeed if the framerate is too high. Force it to vsync. You should use the newer OldUnreal binaries with SDL2 instead! */
     {"ut-bin", "SDL12COMPAT_SYNC_TO_VBLANK", "1"},
-    {"ut-bin", "SDL12COMPAT_MAX_FPS", "120"}
+    {"ut-bin", "SDL12COMPAT_MAX_FPS", "120"},
+
+    /* Jamestown (the old Humble Bundle version from 2011) doesn't render in-game with GL scaling enabled. */
+    {"Jamestown-x86", "SDL12COMPAT_OPENGL_SCALING", "0"},
+    {"Jamestown-amd64", "SDL12COMPAT_OPENGL_SCALING", "0"},
+
 #else
     /* TODO: Add any quirks needed for this system. */