Tweak dependencies for the Windows build job

Tweak dependencies for the Windows build job

Since the Windows build job does not use the files created as a result
of running "autoreconf -fi" in the "autoreconf:sid:amd64" job, set its
dependencies to an empty list.

Since it is currently not possible to use "needs: []" for jobs which do
not belong to the first stage of a pipeline, set the "needs" key for the
Windows build job to the "autoreconf:sid:amd64" job so that all build
jobs are started at the same time (without this change, the Windows
build job does not start until all jobs in the "precheck" stage are
finished).

As a side note, these changes also attempt to eliminate intermittent,
bogus GitLab error messages ("There has been a missing dependency
failure").