pgsql: Use PostgresSigHupHandler in more places.

Use PostgresSigHupHandler in more places.

There seems to be no reason for every background process to have
its own flag indicating that a config-file reload is needed.
Instead, let's just use ConfigFilePending for that purpose
everywhere.

Patch by me, reviewed by Andres Freund and Daniel Gustafsson.

Discussion: http://postgr.es/m/CA+TgmoZwDk=BguVDVa+qdA6SBKef=PKbaKDQALTC_9qoz1mJqg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/1e53fe0e70f610c34f4c9e770d108cd94151342c

Modified Files
--------------
src/backend/postmaster/autovacuum.c | 30 ++++++++----------------------
src/backend/postmaster/bgwriter.c | 20 +++-----------------
src/backend/postmaster/checkpointer.c | 24 +++++-------------------
src/backend/postmaster/pgarch.c | 25 +++++--------------------
src/backend/postmaster/pgstat.c | 28 +++++++---------------------
src/backend/postmaster/walwriter.c | 20 +++-----------------
src/backend/replication/logical/launcher.c | 23 +++--------------------
src/backend/replication/logical/worker.c | 23 +++--------------------
8 files changed, 37 insertions(+), 156 deletions(-)