pgsql: Force LC_COLLATE to C in postmaster.

Force LC_COLLATE to C in postmaster.

Avoid dependence on setlocale().

strcoll(), etc., are not called directly; all collation-sensitive
calls should go through pg_locale.c and use the appropriate
provider. By setting LC_COLLATE to C, we avoid accidentally depending
on libc behavior when using a different provider.

No behavior change in the backend, but it's possible that some
extensions will be affected. Such extensions should be updated to use
the pg_locale_t APIs.

Discussion: https://postgr.es/m/9875f7f9-50f1-4b5d-86fc-ee8b03e8c162@eisentraut.org
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/5e6e42e44fe10cab616b4fbe9725df03c987c90a

Modified Files
--------------
doc/src/sgml/catalogs.sgml            |  2 +-
doc/src/sgml/charset.sgml             |  2 +-
doc/src/sgml/ref/create_database.sgml | 45 ++++++++++++++++++-----------------
doc/src/sgml/ref/createdb.sgml        |  3 ++-
src/backend/main/main.c               | 16 ++++++++-----
src/backend/utils/init/postinit.c     | 11 ++++-----
6 files changed, 42 insertions(+), 37 deletions(-)