Add spec aarch64-apple-darwin9 (Apple Silicon)

[iamFIREcracker]

This PR adds specs for Apple Silicon, finally making it possible to run Sketch on newer macs (see related links below). Also, tested on a MacBook Air M2 and it all seems to be working just fine.

Steps to regenerate the specs (I used nix)

First off, force quicklisp to use a version of cl-sdl2 which supports Apple Silicon (e.g., you can clone my fork into ~/quicklisp/local-projects, or wherever your quicklisp installation lives). Note: you won't need this step anymore once changes are merged upstream (see: lispgames/cl-sdl2#167).

Next, drop the following lines in a file named shell.nix at the root of the repository, and then, in the same directory, run nix-shell (this will take care of installing SDL2_ttf and c2ffi).

shell.nix

let
  pkgs =
    import (
      fetchTarball {
        name = "nixos-23.05_2023-09-18";
        url =
          "https://github.com/NixOS/nixpkgs/archive/f81112bbb0f357b80333300c4702ff7538096156.tar.gz";
        sha256 = "0pxhiggxl5drnpva9287w136rrykcd7xk1nyh655wgf6sb38a82k";
      }
    )
    {};
in
  pkgs.mkShell {
    packages = [
      pkgs.SDL2
      pkgs.SDL2_ttf
      pkgs.c2ffi
    ];
    LD_LIBRARY_PATH = "${pkgs.SDL2}/lib:${pkgs.SDL2_ttf}/lib";
    /* libffi-types__gtove.c has an include for ffi/ffi.h; installing libffi
    would not work because ${pkgs.libffe.dev}/include contains "ffi.h" and
    not "ffi/ffi.h"; so the solution, for now, is to rely on MacOS default
    includes */
    C_INCLUDE_PATH = "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/:${pkgs.SDL2_ttf}/include";
  }

Remove the already existing specs (autowrap will try to generate the spec files only if missing):

$ rm -f src/spec/SDL_ttf.*.spec

Load :SDL2-TTF (this will get autowrap to generate the various spec files:

$ sbcl \
	--load "sdl2-ttf.asd" \
	--eval "(ql:quickload '(:sdl2-ttf))" \
	--eval "(uiop:quit)"

Related issues

• M1 mac + sdl2 error lispgames/cl-sdl2#154
• Compiling fails on M1 with sbcl lispgames/cl-sdl2#147
• Loading sdl2 on macOS Monterey fails: M1/arm64 not supported lispgames/cl-sdl2#144

PS. autowrap file seems to refer to the header file by its wrong name, so I went on and renamed that to match what was used. Let me know if you instead preferred me to create a separate PR for that.