Logging, macros, and building: - Changes logging API to accept the `Location` of the log statement. Fixes OpenPAM implementation. - Stops publicly exporting doc macros. - Uses dlopen to detect the PAM library rather than header jankery.

FROM docker.io/debian:stable

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