pgsql: Convert some extern variables to static

Convert some extern variables to static

These probably should have been static all along, it was only
forgotten out of sloppiness.

Reviewed-by: Andres Freund <andres(at)anarazel(dot)de>
Discussion: https://www.postgresql.org/message-id/flat/e0a62134-83da-4ba4-8cdb-ceb0111c95ce(at)eisentraut(dot)org

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/720b0eaae9b8a8326b2b6a6ff88fca4f47c631d4

Modified Files
--------------
contrib/isn/EAN13.h | 4 +-
contrib/isn/ISBN.h | 8 +--
contrib/isn/ISMN.h | 4 +-
contrib/isn/ISSN.h | 4 +-
contrib/isn/UPC.h | 4 +-
src/backend/commands/user.c | 4 +-
src/backend/postmaster/launch_backend.c | 2 +-
src/backend/replication/logical/slotsync.c | 2 +-
src/backend/replication/logical/worker.c | 2 +-
src/backend/utils/misc/guc_tables.c | 7 ++-
src/bin/pg_archivecleanup/pg_archivecleanup.c | 15 ++---
src/bin/pg_basebackup/bbstreamer_file.c | 4 +-
src/bin/pg_basebackup/bbstreamer_gzip.c | 4 +-
src/bin/pg_basebackup/bbstreamer_inject.c | 2 +-
src/bin/pg_basebackup/bbstreamer_lz4.c | 4 +-
src/bin/pg_basebackup/bbstreamer_tar.c | 6 +-
src/bin/pg_basebackup/bbstreamer_zstd.c | 4 +-
src/bin/pg_basebackup/walmethods.c | 4 +-
src/bin/pg_checksums/pg_checksums.c | 4 +-
src/bin/pg_combinebackup/pg_combinebackup.c | 2 +-
src/bin/pg_rewind/pg_rewind.c | 12 ++--
src/bin/pg_test_timing/pg_test_timing.c | 2 +-
src/bin/pgbench/pgbench.c | 67 +++++++++++-----------
src/bin/scripts/vacuumdb.c | 2 +-
src/pl/plpgsql/src/pl_handler.c | 4 +-
src/test/isolation/isolation_main.c | 6 +-
src/test/modules/dummy_index_am/dummy_index_am.c | 6 +-
src/test/modules/libpq_pipeline/libpq_pipeline.c | 4 +-
.../test_json_parser_incremental.c | 2 +-
29 files changed, 99 insertions(+), 96 deletions(-)