diffutils: nvhpc not 11 compliant for __builtin_add_overflow

[cessenat]

nvhpc even latest 22.1 fails to compile diffutils 3.8 because it erroneously pretends to be 11 compliant but this is not true.
Paul Eggert from UCLA gave me a patch for latest diffutils master, I adapted it for diffutils 3.8.

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[cessenat]

Hello @eugeneswalker would'nt you like to review that ?
Strange no one met the same problem, I got it with all nvhpc versions and systems I have.

[cessenat]

Sorry @alalazo for asking, but would you review this ? I'm puzzled no one met this issue, maybe because it is a core-package.

[cessenat]

Hello @sethrj would you agree to review that ? This PR is made so that nvhpc compiles latest difutils.

[sethrj]

Seems reasonable, and it will only affect nvhpc. I wonder if other compilers will hit this too.

[cessenat]

Seems reasonable, and it will only affect nvhpc. I wonder if other compilers will hit this too.

I don't think so. Thanks for review.