[bug#31430] [PATCH 2/3] gnu: Add xtl.

[Fis Trivial]

Ludovic Courtès writes:

> Fis Trivial <address@hidden> skribis:
>
>> * gnu/packages/cpp.scm (xtl): New variable.
>
> [...]
>
>> +         (replace 'check
>> +           (lambda* _
>> +             (invoke "make" "test_xtl")
>> +             (chdir "test")
>> +             (invoke "./test_xtl")
>> +             (chdir ".."))))))
>
> Instead of chdir, rather do:
>
>   (with-directory-excursion "test"
>     (invoke "./test_xtl")
>     #t)
>
>> +    (home-page "https://github.com/QuantStack/xtl";)
>> +    (build-system cmake-build-system)
>> +    (synopsis "C++ template library providing some basic tools")
>> +    (description "xtl is a C++ header-only template library providing basic
>> +tools (containers, algorithms) used by other quantstack packages")
>
> I know it’s from upstream, but please s/quantstack/QuantStack/ and add a
> period at the end.
>
> Could you send an updated patch?
>
> Ludo’.

Thanks for the review. I will resend the patches series in a few days if
unbundling json-modern-cxx went well.