Revert "test-suite target now depends upon combine"

This reverts commit e0790b5281ebd0ca01b0a230e77aa8d7ad9d8b57.

It is better to leave this out, because the availability of the combined
source file will trigger the combined test cases, which in turn makes
test-driven development frustrating because you are spammed with combined
errors, which duplicates the first-encountered case error.