Do not include Win64 executable in the win-openGL client

Fixes https://trac.openmicroscopy.org.uk/ome/ticket/11900

To test this PR, open the various Windows artifacts  produced by the merge builds for each Ice version. Both the `win-openGL` and the `win64-openGL` clients should only contain one single Insight executable. Make sure each of these executables work as expected (log in, browse, open image).