pgsql: Convert elog(LOG) calls to ereport() where appropriate

Convert elog(LOG) calls to ereport() where appropriate

User-visible log messages should go through ereport(), so they are
subject to translation.  Many remaining elog(LOG) calls are really
debugging calls.

Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://www.postgresql.org/message-id/flat/92d6f545-5102-65d8-3c87-489f71ea0a37%40enterprisedb.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/eb93f3a0b633ad6afb0f37391b87f460c4b0663b

Modified Files
--------------
src/backend/access/gist/gist.c           |   5 +-
src/backend/access/nbtree/nbtpage.c      |   7 ++-
src/backend/access/transam/xlog.c        | 100 +++++++++++++++++++++----------
src/backend/libpq/auth.c                 |   7 ++-
src/backend/libpq/hba.c                  |   3 +-
src/backend/libpq/pqcomm.c               |  56 +++++++++++------
src/backend/postmaster/bgworker.c        |   8 +--
src/backend/postmaster/pgstat.c          |  17 +++---
src/backend/postmaster/postmaster.c      |  44 +++++++++-----
src/backend/replication/logical/origin.c |   9 +--
src/backend/storage/file/fd.c            |   8 ++-
src/backend/utils/misc/guc.c             |   2 +-
12 files changed, 172 insertions(+), 94 deletions(-)