[build2] Constraining the C++ standard

[Fabian Meyer]

Sure, go ahead and feel free to file a PR :)

06.07.2023 23:00:20 lyrahgames <lyrahgames at mailbox.org>:

> 
> Fabian Meyer <fabian.meyer at posteo.de> wrote:
> 
>> Just one note:  libcxxopts is already published on cppget
>> https://cppget.org/libcxxopts?q=cxxopt
>> I think I just did not port the tests because of the autoptr problem you have. I only ported the examples.
> 
> Thank you so much for the notice. That is very nice.
> Unfortunately, it seems that I have not been paying enough attention
> and may have done some useless extra work.
> If you would be interested, I could propose a pull request
> to the already existing package repository to add some functionality of my trial.
> Otherwise, I will archive my repository for documentation.