Adjust commentary in regc_pg_locale.c to remove mention of the possibility
of not having <wctype.h> functions, since we no longer consider that.

Eliminate duplicate code in wparser_def.c by generalizing the p_iswhat
macro to take a parameter saying what to return for non-ASCII chars
in C locale.  (That's not really a consequence of the
USE_WIDE_UPPER_LOWER-ectomy, but I noticed it while doing that.)

…on_HL() function.

tags: pg_tsparser

[refer #PGPRO-4978] Update the .gitignore file.

tags: pg_tsparser

In PostgreSQL version 12 or higher it's more effecient to use the function
pg_strtoint32 instead (see the commit 86eaf208ea048936df6be77276a246d3f92e9620).
And in PostgreSQL 15 the function pg_atoi was removed altogether (see the commit
73508475d69e90f98ebd9b7e1a5933a26a49c5e9). Therefore if possible use the
function pg_strtoint32 instead.

PGPRO-6866: do not use the function pg_atoi if possible

…=C for 16+

See the commit f413941f41d370a7893caa3e6ed384b89a0577fd (Fix t_isspace(), etc.,
when datlocprovider=i and datctype=C.) in PostgreSQL 16+. A fix for previous
major versions will be added later.

Tags: icu, pg_tsparser

[PGPRO-8706] Backport pg_tsparser fix

Add meson.build file to support building from the contrib source tree.