Avoid creating testtablespace directories where not wanted.
Recently we refactored things so that pg_regress makes the
"testtablespace" subdirectory used by the core regression tests,
instead of doing that in the makefiles. That had the undesirable
side effect of making such a subdirectory in every directory that
has "input" or "output" test files. Since these subdirectories
remain empty, git doesn't complain about them, but nonetheless
they're clutter.
To fix, invent an explicit --make-testtablespace-dir switch,
so that pg_regress only makes the subdirectory when explicitly
told to.
Discussion: https://postgr.es/m/
2854388.
1621284789@sss.pgh.pa.us