meson: make nologin path build time configurable

meson: make nologin path build time configurable

Some distros install nologin as /usr/sbin/nologin, others as
/sbin/nologin.
Since we can't really on merged-usr everywhere (where the path wouldn't
matter), make the path build time configurable via -Dnologin-path=.

Closes #13028

(cherry picked from commit 6db904625d413739c480ddbe7667d3f40acc4ae0)

Gbp-Pq: Name meson-make-nologin-path-build-time-configurable.patch