pgsql: Rename pg_sequence_read_tuple() to pg_get_sequence_data()

Rename pg_sequence_read_tuple() to pg_get_sequence_data()

This commit removes log_cnt from the tuple returned by the SQL function.
This field is an internal counter that tracks when a WAL record should
be generated for a sequence, and it is reset each time the sequence is
restored or recovered.  It is not necessary to rebuild the sequence DDL
commands for pg_dump and pg_upgrade where this function is used.  The
field can still be queried with a scan of the "table" created
under-the-hood for a sequence.

Issue noticed while hacking on a feature that can rely on this new
function rather than pg_sequence_last_value(), aimed at making sequence
computation more easily pluggable.

Bump catalog version.

Reviewed-by: Nathan Bossart
Discussion: https://postgr.es/m/Zsvka3r-y2ZoXAdH@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a83a944e9fdd573802c82d961126ba07bfb65f98

Modified Files
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src/backend/commands/sequence.c        | 17 ++++++++---------
src/bin/pg_dump/pg_dump.c              |  4 ++--
src/include/catalog/catversion.h       |  2 +-
src/include/catalog/pg_proc.dat        |  8 ++++----
src/test/regress/expected/sequence.out | 10 +++++-----
src/test/regress/sql/sequence.sql      |  4 ++--
6 files changed, 22 insertions(+), 23 deletions(-)