change build system to CMake and use SDL3 for everything

libs/SDL3/docs/README-porting.md

@@ -0,0 +1,65 @@
+Porting
+=======
+
+* Porting To A New Platform
+
+  The first thing you have to do when porting to a new platform, is look at
+include/SDL_platform.h and create an entry there for your operating system.
+The standard format is "SDL_PLATFORM_X", where X is the name of the OS.
+Ideally SDL_platform_defines.h will be able to auto-detect the system it's building
+on based on C preprocessor symbols.
+
+There are two basic ways of building SDL at the moment:
+
+1. CMake:  cmake -S . -B build && cmake --build build && cmake --install install
+
+   If you have a system that supports CMake, then you might try this.  Edit CMakeLists.txt,
+
+   take a look at the large section labelled:
+
+	"Platform-specific options and settings!"
+
+   Add a section for your platform, and then re-run 'cmake -S . -B build' and build!
+
+2. Using an IDE:
+
+   If you're using an IDE or other non-configure build system, you'll probably want to create a custom `SDL_build_config.h` for your platform.  Edit `include/build_config/SDL_build_config.h`, add a section for your platform, and create a custom `SDL_build_config_{platform}.h`, based on `SDL_build_config_minimal.h` and `SDL_build_config.h.cmake`
+
+   Add the top level include directory to the header search path, and then add
+   the following sources to the project:
+
+	src/*.c
+	src/atomic/*.c
+	src/audio/*.c
+	src/cpuinfo/*.c
+	src/events/*.c
+	src/file/*.c
+	src/haptic/*.c
+	src/joystick/*.c
+	src/power/*.c
+	src/render/*.c
+	src/render/software/*.c
+	src/stdlib/*.c
+	src/thread/*.c
+	src/timer/*.c
+	src/video/*.c
+	src/audio/disk/*.c
+	src/audio/dummy/*.c
+	src/filesystem/dummy/*.c
+	src/video/dummy/*.c
+	src/haptic/dummy/*.c
+	src/joystick/dummy/*.c
+	src/thread/generic/*.c
+	src/timer/dummy/*.c
+	src/loadso/dummy/*.c
+
+
+Once you have a working library without any drivers, you can go back to each
+of the major subsystems and start implementing drivers for your platform.
+
+If you have any questions, don't hesitate to ask on the SDL mailing list:
+	http://www.libsdl.org/mailing-list.php
+
+Enjoy!
+	Sam Lantinga				(slouken@libsdl.org)
+