Change in flashrom[master]: hwaccess.c: Fix PowerPC memory barrier

[Nico Huber (Code Review)]

Attention is currently required from: Angel Pons.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/52470 )

Change subject: hwaccess.c: Fix PowerPC memory barrier
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Patch Set 4:

(1 comment)

Patchset:

PS4:
> What part of this is hard to predict?

If it will compile. We are outside of ISO C here. The weirdest part:
ISO C lists `asm` as a common extension, however, if you enable strict
ISO C conformance (which another patch tried), the `asm` keyword
doesn't exist anymore because it's a valid identifier in C (strictly
speaking).

We don't know what compiler (version) will be used. As I said above, we
can raise the bar but I think we should only do it after the release.
> Isn't this fixing a compilation error (specifically guarded with IS_PPC)

It is. But fixing things for one compiler/case can break them for another.