[Incomplete] Initial SDL3 support

Add VL, SD, and IN backends for SDL3. We do this instead of using the
combined SDL1/2 backends for SD and IN, as so many functions have been
renamed. This does present some problems, as otherwise they share a lot
of code, so one will likely end up outdated.

Ideally, some of the 'generic' code, particularly in id_sd, can be split
out a bit.

Otherwise, this is still incomplete:
- Some code, particularly in id_sd, is dead.
- Graphics is probably broken on big-endian. (Though even SDL2 seemed
  broken on NetBSD/arm64eb, though that's weird enough I can't guarantee
  it'd work anyway.)
- The pkg-config bits in the makefile are a bit ugly.
- We'll possibly want support for vendored SDL3 at some point, too.
- One day we'll want an SDL3_gpu based VL backend, but the renderer is
  good for now.
- The SDL3 API is changing rapidly, so this needs to keep up

One notable change is that all includes of "SDL.h" need to be replaced
with an include of "ck_cross.h", which has the correct logic to include
"SDL3/SDL.h" where needed. WITH_SDL is now set to 3 for SDL3 builds.

CMakeLists.txt

@@ -161,6 +161,21 @@ elseif(RENDERER STREQUAL "sdl1")
 		${SDL_INCLUDE_DIR}
 	)
 	add_definitions(-DWITH_SDL)
+elseif(RENDERER STREQUAL "sdl3")
+	message(STATUS "Using SDL3 renderer backend")
+	find_package(SDL3 REQUIRED)
+	set(OMNISPEAK_PLATFORM_SRCS
+		src/id_in_sdl3.c
+		src/id_sd_sdl3.c
+		src/id_vl_sdl3.c
+	)
+	set(OMNISPEAK_PLATFORM_LIBRARIES
+		${SDL3_LIBRARIES}
+	)
+	include_directories(
+		${SDL3_INCLUDE_DIRS}
+	)
+	add_definitions(-DWITH_SDL=3)
 else()
 	message(WARNING "Using NULL platform layer.")
 	set(OMNISPEAK_PLATFORM_SRCS

src/Makefile

@@ -33,6 +33,7 @@ This Makefile supports the following options:
 		  sdl2sw  = SDL 2.0 + Software SDL_Renderer
 		  sdl2gl  = SDL 2.0 + OpenGL 2.0 (default)
 		  sdl2vk  = SDL 2.0 + Vulkan (experimental)
+		  sdl3    = SDL 3.0 + SDL_Renderer
 		  null    = dummy renderer
 
   WITH_KEEN4    whether to include support for Keen 4: Secret of the Oracle (0/1; default: on)
@@ -352,6 +353,12 @@ ifeq ($(RENDERER), sdl2vk)
 	CXXFLAGS += -I$(OBJDIR) #For generated SPIR-V headers
 endif
 
+ifeq ($(RENDERER), sdl3)
+	RENDER_OBJS = id_vl_sdl3.o id_sd_sdl3.o id_in_sdl3.o
+	SDL_CFLAGS = `pkg-config sdl3 --cflags` -DWITH_SDL=3
+	SDL_LIBS = `pkg-config sdl3 $(SDL_LIB_QUERY)`
+endif
+
 ifeq ($(RENDERER), dos)
 	RENDER_OBJS = id_vl_dos.o id_sd_dos.o id_in_dos.o
 endif

src/ck_cross.h

@@ -7,7 +7,11 @@
 #include <stdio.h>
 
 #ifdef WITH_SDL
+#if WITH_SDL == 3
+#include <SDL3/SDL.h>
+#else
 #include "SDL.h"
+#endif
 #if SDL_BYTEORDER == SDL_BIG_ENDIAN
 #define CK_CROSS_IS_BIGENDIAN
 #elif (SDL_BYTEORDER == SDL_LIL_ENDIAN)

src/ck_main.c

@@ -43,9 +43,6 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include <stdlib.h>
 #include <string.h>
 
-#ifdef WITH_SDL
-#include <SDL.h> // For main (SDL_main) function prototype
-#endif
 /*
  * The 'episode' we're playing.
  */

src/id_ca.c

@@ -34,9 +34,6 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
 #include <stdio.h>
 #include <string.h>
-#ifdef WITH_SDL
-#include "SDL.h"
-#endif
 
 #define CA_THREEBYTEHEADERS