pgsql: Generate GUC tables from .dat file

Generate GUC tables from .dat file

Store the information in guc_tables.c in a .dat file similar to the
catalog data in src/include/catalog/, and generate a part of
guc_tables.c from that.  The goal is to make it easier to edit that
information, and to be able to make changes to the downstream data
structures more easily.  (Essentially, those are the same reasons as
for the original adoption of the .dat format.)

Reviewed-by: John Naylor <johncnaylorls@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: David E. Wheeler <david@justatheory.com>
Discussion: https://www.postgresql.org/message-id/flat/dae6fe89-1e0c-4c3f-8d92-19d23374fb10%40eisentraut.org

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/63599896545c7869f7dd28cd593e8b548983d613

Modified Files
--------------
src/backend/utils/.gitignore              |    1 +
src/backend/utils/Makefile                |   11 +-
src/backend/utils/misc/gen_guc_tables.pl  |  131 +
src/backend/utils/misc/guc_parameters.dat | 3473 +++++++++++++++++++++
src/backend/utils/misc/guc_tables.c       | 4736 +----------------------------
src/bin/pg_dump/dumputils.c               |    2 +-
src/include/libpq/libpq.h                 |   18 +
src/include/utils/.gitignore              |    1 +
src/include/utils/guc.h                   |   23 +
src/include/utils/inval.h                 |   18 +
src/include/utils/meson.build             |    7 +
src/timezone/pgtz.c                       |    4 +-
12 files changed, 3683 insertions(+), 4742 deletions(-)