c2ffi failing on ARM64 when building cl-sdl2

SDL is cloned from Github into /opt/sdl and itself buids fine.

My test script:

#!/bin/bash
# set -x

C2FFI_EXE="c2ffi"
CLANG_VERSION=12
LLVM_VERSION=12
CLANG_INCLUDE_DIR="/usr/lib/clang/$CLANG_VERSION/include"
LLVM_INCLUDE_DIR="/usr/lib/llvm-$LLVM_VERSION/include"

SYS_INCLUDE_DIR="/usr/include"

SDL_H_FILE="/opt/common-lisp/quicklisp/dists/quicklisp/software/cl-sdl2-20211230-git/src/spec/SDL2.h"
MACRO_FILE="/home/frgo/tmp/macros.c"
ARCHITECTURE="aarch64-pc-linux-gnu"
SDL_INCLUDE_DIR="/opt/sdl/include"
C2FFI_DRIVER="null"

LOG_FILE="/home/frgo/tmp/c2ffi.log"

$C2FFI_EXE $SDL_H_FILE \
        -D $C2FFI_DRIVER \
        -M $MACRO_FILE \
        -A $ARCHITECTURE \
        -i $SYS_INCLUDE_DIR \
        -i $CLANG_INCLUDE_DIR \
        -i $LLVM_INCLUDE_DIR \
        -i $SDL_INCLUDE_DIR 2>&1 > $LOG_FILE
        
Running this gives:

  ~/tmp ❯ ./c2ffi.sh                                                                                                                                  frgo@goeded01  09:44:24
In file included from /opt/common-lisp/quicklisp/dists/quicklisp/software/cl-sdl2-20211230-git/src/spec/SDL2.h:1:
In file included from /opt/sdl/include/SDL2/SDL.h:38:
In file included from /opt/sdl/include/SDL2/SDL_cpuinfo.h:81:
/usr/lib/llvm-12/lib/clang/12.0.0/include/arm_neon.h:1730:47: error: passing 'int8x16_t' (aka 'signed char') to parameter of incompatible type '__attribute__((__vector_size__(16 * sizeof(signed char)))) signed char' (vector of 16 'signed char' values)
  __ret = (uint8x16_t) __builtin_neon_vabdq_v((int8x16_t)__p0, (int8x16_t)__p1, 48);
  
  ... loads more of similar error messages.
  

Solution: Put the following content in SDL2.h:

#define SDL_DISABLE_ARM_NEON_H 1
#include <SDL2/SDL.h>
#include <SDL2/SDL_syswm.h>