Commit c3382a3c3, which moved the implementation of PG_TEST_EXTRA
from src/test/Makefile into individual test scripts, broke the
directions given in the subdirectory README files about how to run
these tests by hand. Update. Also mention wal_consistency_checking
in recovery/README --- that omission isn't the fault of c3382a3c3,
but it's still an omission.
Rearrange src/test/perl/README so that the first section is more
clearly "how to run these tests", and the rest "how to write new
tests". Add some basic info there about debugging test failures.
Then, add cross-refs to that READNE from other READMEs that
describe how to run TAP tests.
Per suggestion from Kevin Burke, though this is not his original
patch.
Discussion: https://postgr.es/m/CAKcy5eiSbwiQnmCfnOnDCVC7B8fYyev3E=6pvvECP9pLE-Fcuw@mail.gmail.com
Explain the difference between "make check" and "make installcheck".
Mention the need for --enable-tap-tests (only some of these did so
before). Standardize their wording about how to run the tests.
