Enable Python Limited API for PL/Python on MSVC

Activate Python "Limited API" in PL/Python

Prepare for Python "Limited API" in PL/Python

Remove obsolete Python version check

Remove bogus const qualifier on PageGetItem() argument

Add some more use of Page/PageData rather than char *

Add const qualifiers to bufpage.h

Add PageData C type

doc PG 18 relnotes: Add migration note about tsearch

Remove ts_locale.c's lowerstr()

Remove ts_locale.c's t_isdigit(), t_isspace(), t_isprint()

oauth: Correct test dependency on oauth_hook_client

meson: Add test dependencies for test_json_parser

meson: Narrow dependencies for 'install-quiet' target

meson: Improve dependencies for tmp_install test target

meson: Add pg_regress_ecpg to ecpg test dependencies

Return yyparse() result not via global variable

Remove flex version checks

Drop warning-free support for Flex 2.5.35

plpgsql: pure parser and reentrant scanner

flex code modernization: Replace YY_EXTRA_TYPE define with flex option

IWYU widely useful pragmas

Add a bit of documentation related to IWYU

IWYU pragmas for catalog headers

Downgrade error in object_aclmask_ext() to internal

Downgrade errors in object_ownercheck() to internal

meson: Fix missing name arguments of cc.compiles() calls

Remove useless configure check

Remove pgrminclude and associated scripts

Remove pgrminclude annotations