Re: change "microcode: Use fallthrough attribute on clang 10 and 11 too." broke the build for me

[Taylor R Campbell]

> Date: Mon, 15 Feb 2021 14:20:22 -0800
> From: Chris Hanson <cph@chris-hanson.org>
> 
> Where did you find out about W^X ?
> 
> I have an x86-64 machine running macos 11.2 and scheme works fine there, 
> mostly. Specifically, if I build the normal binaries, they seem to run 
> just fine. However, if I build a macos app, it fails to run at all. 
> Perhaps the W^X restriction applies only to apps?

https://developer.apple.com/documentation/apple_silicon/porting_just-in-time_compilers_to_apple_silicon

   When memory protection is enabled, a thread cannot write to a
   memory region and execute instructions in that region at the same
   time. Apple silicon enables memory protection for all apps,
   regardless of whether they adopt the Hardened Runtime. Intel-based
   Mac computers enable memory protection only for apps that adopt the
   Hardened Runtime.