sdl2-compat: cmake: detect RISCOS platform before GNU/Hurd

SDL Commits
1 
From 96d697b5dfc03e3d9e75a0a53933f4f4c1bad93c Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Fri, 8 Aug 2025 04:55:32 +0200
Subject: [PATCH] cmake: detect RISCOS platform before GNU/Hurd

---
 cmake/sdlplatform.cmake | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/cmake/sdlplatform.cmake b/cmake/sdlplatform.cmake
index 13da4c22..6dbc1d4c 100644
--- a/cmake/sdlplatform.cmake
+++ b/cmake/sdlplatform.cmake
@@ -21,6 +21,8 @@ macro(SDL_DetectCMakePlatform)
     set(SDL_CMAKE_PLATFORM n3ds)
   elseif(PS2)
     set(SDL_CMAKE_PLATFORM ps2)
+  elseif(RISCOS)
+    set(SDL_CMAKE_PLATFORM RISCOS)
   elseif(VITA)
     set(SDL_CMAKE_PLATFORM Vita)
   elseif(CMAKE_SYSTEM_NAME MATCHES ".*Linux")
@@ -32,6 +34,7 @@ macro(SDL_DetectCMakePlatform)
   elseif(CMAKE_SYSTEM_NAME MATCHES "kOpenBSD.*|OpenBSD.*")
     set(SDL_CMAKE_PLATFORM OpenBSD)
   elseif(CMAKE_SYSTEM_NAME STREQUAL "GNU")
+    # GNU/Hurd must be checked AFTER RISCOS
     set(SDL_CMAKE_PLATFORM Hurd)
   elseif(CMAKE_SYSTEM_NAME MATCHES ".*BSDI.*")
     set(SDL_CMAKE_PLATFORM BSDi)