Report test_atomic_ops() failures consistently, via macros.
This prints the unexpected value in more failure cases, and it removes
forty-eight hand-maintained error messages. Back-patch to 9.5, which
introduced these tests.
Reviewed (in an earlier version) by Andres Freund.
Discussion: https://postgr.es/m/
20190915160021.GA24376@alvherre.pgsql