Re: LogwrtResult contended spinlock

Couldn't push: I tested with --disable-atomics --disable-spinlocks and
the tests fail because the semaphore for the atomic variables is not
always initialized.  This is weird -- it's like a client process is
running at a time when StartupXLOG has not initialized the variable ...
so the initialization in the other place was not completely wrong.
I'll investigate after lunch.  Here's v16.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"XML!" Exclaimed C++.  "What are you doing here? You're not a programming
language."
"Tell that to the people who use me," said XML.
https://burningbird.net/the-parable-of-the-languages/