pgpool: Feature: Import PostgreSQL 18 new parser.

Feature: Import PostgreSQL 18 new parser.

Major changes of PostgreSQL 18 parser include:
- Allow generated columns to be virtual
- Add OLD/NEW support to RETURNING in DML queries
- Addition of various constraints (e.g. WITHOUT OVERLAPS, ENFORCED / NOT ENFORCED)
- etc.

Branch
------
master

Details
-------
https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=df277163720a248f108192329de58077cd35ea4e

Modified Files
--------------
src/include/parser/gramparse.h | 4 +-
src/include/parser/keywords.h | 4 +-
src/include/parser/kwlist.h | 9 +-
src/include/parser/kwlist_d.h | 894 ++++++++++++-----------
src/include/parser/makefuncs.h | 5 +-
src/include/parser/miscnodes.h | 53 ++
src/include/parser/nodes.h | 21 +-
src/include/parser/nodetags.h | 801 ++++++++++----------
src/include/parser/parsenodes.h | 177 ++++-
src/include/parser/parser.h | 4 +-
src/include/parser/pg_class.h | 11 +-
src/include/parser/pg_config_manual.h | 72 +-
src/include/parser/pg_list.h | 74 +-
src/include/parser/pg_trigger.h | 6 +-
src/include/parser/pg_wchar.h | 13 +-
src/include/parser/pool_parser.h | 23 +-
src/include/parser/primnodes.h | 120 ++-
src/include/parser/scanner.h | 6 +-
src/include/parser/scansup.h | 4 +-
src/include/parser/stringinfo.h | 33 +-
src/include/parser/unicode_east_asian_fw_table.h | 126 ++++
src/include/parser/unicode_nonspacing_table.h | 338 +++++++++
src/include/parser/value.h | 4 +-
src/main/pgpool_logger.c | 2 +-
src/parser/copyfuncs.c | 180 +++--
src/parser/gram.y | 737 ++++++++++++-------
src/parser/gram_minimal.y | 723 +++++++++++-------
src/parser/gram_template.y | 725 +++++++++++-------
src/parser/keywords.c | 4 +-
src/parser/kwlookup.c | 4 +-
src/parser/list.c | 4 +-
src/parser/makefuncs.c | 93 ++-
src/parser/outfuncs.c | 144 +++-
src/parser/parser.c | 4 +-
src/parser/scan.l | 72 +-
src/parser/scansup.c | 4 +-
src/parser/snprintf.c | 95 ++-
src/parser/stringinfo.c | 79 +-
src/parser/value.c | 4 +-
src/parser/wchar.c | 554 +++-----------
src/rewrite/pool_timestamp.c | 12 +-
src/tools/pgindent/enums.list | 2 +-
src/tools/pgindent/typedefs.list | 2 +-
43 files changed, 3818 insertions(+), 2428 deletions(-)