[Issue 12891] add atomicFetchAdd and atomicFetchSub to core.atomic

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=12891

--- Comment #6 from Martin Nowak <code at dawg.eu> ---
Created attachment 1508
  --> https://issues.dlang.org/attachment.cgi?id=1508&action=edit
atomic fetch add for x64

Implementation of atomicOp!"+=" (fetch_add) for X86_64.

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