Fix 'make check-old' warnings when WITHOUT_TESTS is set.
Fix 'make check-old' warnings when WITHOUT_TESTS is set.

This is a MFC of r258025 and r257940, both of which resolve issues with
dynamically setting the list of obsolete files based on the contents
of /usr/tests.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase