Auto-detection silently turns off test/install (and test/build) when their .sql files go missing #147

Claude here, filing this at the maintainer's request.

Problem: when PGXNTOOL_ENABLE_TEST_INSTALL is unset (the default), base.mk enables test/install only if test/install/*.sql exists. If a project that relies on test/install loses those files (an accidental delete, a rename, a bad merge), the feature quietly turns off. make test then runs the suite with no install step, and the result is a pile of failures in unrelated-looking tests rather than one error that names the cause.

The only guard today is for each project to set PGXNTOOL_ENABLE_TEST_INSTALL = yes, which makes a missing test/install/*.sql a make-time error. A project has to know to do that. Postgres-Extensions/trunklet#10 does it for exactly this reason.

PGXNTOOL_ENABLE_TEST_BUILD uses the same auto-detection, with a quieter failure: if test/build/*.sql disappears, the build check is skipped and nothing fails at all.

No fix is proposed here.