[PATCH] atomic: Reinstate HAVE_64B_ATOMICS configure check

[Adhemerval Zanella Netto]

On 16/12/25 12:46, Wilco Dijkstra wrote:
> Hi Adhemerval,
> 
>> Last time I checked I saw that some old gcc versions are not showing the
>> expected results on some ABIs (for instance Ubuntu gcc 13 on armhf). I
>> am not sure how to properly handle it.
> 
> Which case do you mean? On armv7-a 64-bit atomics are always supported,
> so I don't see how it could fail (godbolt confirms it's fine on all released GCC
> versions from 13.1 to 15.1)... However even if it was turned off in some weird
> configuration, it would be the same as it was before with 64-bit atomics
> disabled by default on all 32-bit targets.
> 
> Cheers,
> Wilco

I recall I saw a Linaro armhf buildbot regression after the first try to enable 
this.  But re-testing on an arm64 kernel I do not see this issue anymore, so 
it looks good to me.