The intended purpose of the "autoreconf:sid:amd64" GitLab CI job is to
run "autoreconf -fi" and then pass the updated files on to subsequent
non-Windows build jobs.  However, the artifacts currently created by
that job only include files which are not tracked by Git.  Since we
currently do track e.g. "configure" with Git, the aforementioned job is
essentially a no-op.  Fix by manually specifying the files generated by
the "autoreconf:sid:amd64" job that should be passed on to subsequent
build jobs.