pgsql: pg_verifybackup: Enable WAL parsing for tar-format backups

pg_verifybackup: Enable WAL parsing for tar-format backups

Now that pg_waldump supports reading WAL from tar archives, remove the
restriction that forced --no-parse-wal for tar-format backups.

pg_verifybackup now automatically locates the WAL archive: it looks for
a separate pg_wal.tar first, then falls back to the main base.tar.  A
new --wal-path option (replacing the old --wal-directory, which is kept
as a silent alias) accepts either a directory or a tar archive path.

The default WAL directory preparation is deferred until the backup
format is known, since tar-format backups resolve the WAL path
differently from plain-format ones.

Author: Amul Sul <sulamul@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Jakub Wartak <jakub.wartak@enterprisedb.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Euler Taveira <euler@eulerto.com>
Reviewed-by: Andrew Dunstan <andrew@dunslane.net>
discussion: https://postgr.es/m/CAAJ_b94bqdWN3h2J-PzzzQ2Npbwct5ZQHggn_QoYGhC2rn-=WQ@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/b3cf461b3cf91c586ab94b4dddd6dcd8ff8fec47

Modified Files
--------------
doc/src/sgml/ref/pg_verifybackup.sgml         | 14 ++--
src/bin/pg_verifybackup/pg_verifybackup.c     | 96 ++++++++++++++++++---------
src/bin/pg_verifybackup/t/002_algorithm.pl    |  4 --
src/bin/pg_verifybackup/t/003_corruption.pl   |  4 +-
src/bin/pg_verifybackup/t/007_wal.pl          | 20 +++++-
src/bin/pg_verifybackup/t/008_untar.pl        |  5 +-
src/bin/pg_verifybackup/t/010_client_untar.pl |  5 +-
7 files changed, 91 insertions(+), 57 deletions(-)