sync/atomic: use a better first-store-in-progress marker
Unlike what the comment says, the GC can see this pointer.
Might as well make it a real pointer, even though ^uintptr(0)
isn't currently causing problems.
Removed the comment about GC not seeing the pointer.
Change-Id: I04bc1fd4848698bec6afb79bd5fda671dfc9a073
Reviewed-on: https://go-review.googlesource.com/c/go/+/241661
Run-TryBot: Keith Randall <khr@golang.org> Reviewed-by: Colin Arnott <colin@urandom.co.uk> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Keith Randall <khr@golang.org>