[committed 4/4] d: Merge upstream phobos 574bf883b

[Iain Buclaw]

Excerpts from Andreas Schwab's message of December 9, 2021 11:09 am:
> Breaks aarch64:
> 
> ../../../../libphobos/libdruntime/core/sys/linux/unistd.d:10:15: error: module 'core.sys.linux.syscalls' import 'SystemCall' not found
>    10 | public import core.sys.linux.syscalls : SystemCall;
>       |               ^
> 

Hi Andreas,

Thanks!  I've raised a revert for the change in upstream that broke
this.  Unfortunately they only considered X86 and X86_64 in the change.

Iain.