updating macports-libcxx to llvm-19+

[Chris Jones]

clang-19+ currently does  not build on a number of older OSes, its 
limited to Darwin15 and newer. Before updating macports-libcxx someone 
with the time and inclination should look into that first I would say.

cheers Chris

On 31/03/2025 2:40 pm, Gagan Sidhu via macports-dev wrote:
> any thoughts on this?
> 
> i think it’s time.
> 
> Thanks,
> Gagan