Checkin started some
changes to the way the TCL_ZIP_FILE is built. Unfortunately the changes
lead to failing tests in a common scenario.

If your workspace happens to include an empty directory
(which many do, because of development history), the old system for building
the TCL_ZIP_FILE would not include it, but the new system does include it,
or so I surmise.

The consequence is that several tests (zipfs-0.[345678]) fail in zipfs.test.

I'm open to several points of view whether it is the tests themselves or
the new builder of TCL_ZIP_FILE that is broken, but this should be resolved.