'__config_site' file not found on Ubuntu noble for libc++-18

[mpusz]

For about a week now, libc++-18 does not provide the /usr/include/c++/v1/__config_site header file.

Installed with:

sudo apt install libc++-18-dev libc++abi-18-dev

libc++-19 is OK.

Compilation error log:

In file included from /usr/bin/../include/c++/v1/exception:79:
In file included from /usr/bin/../include/c++/v1/__assert:13:
In file included from /usr/bin/../include/c++/v1/__assertion_handler:13:
/usr/bin/../include/c++/v1/__config:13:10: fatal error: '__config_site' file not found

More info can be found here: https://github.com/mpusz/mp-units/actions/runs/9597865534/job/26467862493.