Just pushed two small commits (d416f7207a39db5ec15c0133904bfd76980a9d4b 2d59d44dd620c597e69f7f1b3d6a9d1b3d410ae3) that made it compile on macos.
When I get some time, I can investigate to see if the option 2. (`Add __CPU_arm64 as a possible value in fastlock.h right next to the __CPU_aarch64`) proposed in a comment above is a good alternative.