SDL_cpuinfo: define __ARM_ARCH=8 for _M_ARM64 Microsoft's compiler doesn't define __ARM_ARCH, but we have several places that use it.
diff --git a/include/SDL_cpuinfo.h b/include/SDL_cpuinfo.h
index 43a8ac5..b5ad0fc 100644
--- a/include/SDL_cpuinfo.h
+++ b/include/SDL_cpuinfo.h
@@ -90,6 +90,7 @@ _m_prefetch(void *__P)
# include <arm64intr.h>
# include <arm64_neon.h>
# define __ARM_NEON 1 /* Set __ARM_NEON so that it can be used elsewhere, at compile time */
+# define __ARM_ARCH 8
# endif
# endif
#endif