please consider creating an empty `/etc/.pwd.lock` when lckpwdf is called

[josch]

When comparing a chroot tarball created with fakechroot and normal chroot there is only a single difference that prevents them from being bit-by-bit identical: the fakechroot tarball is missing /etc/.pwd.lock because fakechroot ignores lckpwdf.

Please consider letting the lckpwdf wrapper create /etc/.pwd.lock inside the chroot to increase compatibility with a chroot created the normal way.

Thanks!