Change in flashrom[master]: tests: Add wraps for __xstat variants of stat

[Nico Huber (Code Review)]

Attention is currently required from: Edward O'Callaghan, Angel Pons, Anastasia Klimchuk.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/58103 )

Change subject: tests: Add wraps for __xstat variants of stat
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Patch Set 4: Code-Review+1

(1 comment)

Commit Message:

https://review.coreboot.org/c/flashrom/+/58103/comment/5cc1f7b6_adc45ed4 
PS2, Line 9: all
> Environment this applies to: __xstat64 wrap is needed to run unit tests with emerge under chromium c […]

That's enough information to retest this if ever necessary. I hope this
will not turn into a cat-and-mouse game where we'd have to add more wraps
in the future. But if it does: we could try to mock the header file as
well.