Add module-specific data support. This adds support for a safe form of `pam_get_data` and `pam_set_data`, where data is (as best as humanly possible) type-safe and restricted to only the module where it was created.

FROM docker.io/debian:stable

RUN apt-get -y update \
    && apt-get -y upgrade \
    && apt-get install -y cargo mercurial \
    && apt-get clean