Add DOS platform options and preseed cache for DJGPP

Disable unsupported SDL features when building for DOS. Add
PreseedDOSCache.cmake to pre-populate CMake cache variables for DJGPP.

Author: AJenbo

CMakeLists.txt

@@ -78,6 +78,7 @@ include("${SDL3_SOURCE_DIR}/cmake/3rdparty.cmake")
 include("${SDL3_SOURCE_DIR}/cmake/PreseedMSVCCache.cmake")
 include("${SDL3_SOURCE_DIR}/cmake/PreseedEmscriptenCache.cmake")
 include("${SDL3_SOURCE_DIR}/cmake/PreseedNokiaNGageCache.cmake")
+include("${SDL3_SOURCE_DIR}/cmake/PreseedDOSCache.cmake")
 
 SDL_DetectCompiler()
 SDL_DetectTargetCPUArchitectures(SDL_CPUS)
@@ -425,6 +426,21 @@ if(VITA)
   set_option(VIDEO_VITA_PVR  "Build with PSVita PVR gles/gles2 support" OFF)
 endif()
 
+if(DOS)
+  set(SDL_GPU              OFF)
+  set(SDL_CAMERA           OFF)
+  set(SDL_HAPTIC           OFF)
+  set(SDL_HIDAPI           OFF)
+  set(SDL_POWER            OFF)
+  set(SDL_SENSOR           OFF)
+  set(SDL_DIALOG           OFF)
+  set(SDL_DUMMYCAMERA      OFF)
+  set(SDL_OFFSCREEN        OFF)
+  set(SDL_RENDER_GPU       OFF)
+  set(SDL_TRAY             OFF)
+  set(SDL_PROCESS          OFF)
+endif()
+
 if (NGAGE)
   set(SDL_GPU              OFF)
   set(SDL_CAMERA           OFF)