E.g. in a derivation attribute `foo = ./bar`, if ./bar is a symlink,
we should copy the symlink to the store, not its target. This restores
the behaviour of Nix <= 2.19.
(cherry picked from commit 26b87e78b5)
Without the change `meson setup` fails on `Gentoo or Debian as those
don't use multicall binary:
$ meson setup ..
...
Executing subproject nix-functional-tests
...
../src/nix-functional-tests/meson.build:24:14: ERROR: Program 'coreutils' not found or not executable
The change always uses `ls` to look `coreutils` up.
Closes: https://github.com/NixOS/nix/issues/11975
