Since 4b2063c3 (Rework static/shared variants into a configure-time build-switch (#688), 2020-05-28)
we iterate over Debug/Release versions via `Configuration:`. But that
commit did leave in some of the old `configuration` entries.

And that was copy pasted into other entries as well.

The fallout is that we have have two environment variables configuration
and Configuration set to something different. And that results in cpack
generating the wrong name for the package.