pgsql: Stop bgworkers during fast shutdown with postmaster in startupp

Stop bgworkers during fast shutdown with postmaster in startup phase

When a postmaster gets into its phase PM_STARTUP, it would start
background workers using BgWorkerStart_PostmasterStart mode immediately,
which would cause problems for a fast shutdown as the postmaster forgets
to send SIGTERM to already-started background workers.  With smart and
immediate shutdowns, this correctly happened, and fast shutdown is the
only mode missing the shot.

Author: Alexander Kukushkin
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/CAFh8B=mvnD8+DZUfzpi50DoaDfZRDfd7S=gwj5vU9GYn8UvHkA@mail.gmail.com
Backpatch-through: 9.5

Branch
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REL9_6_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/f6feb8e3851f8393305ac6d45fe49fe6b9295976

Modified Files
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src/backend/postmaster/postmaster.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)