This is the easiest and cleanest way to get logging into some of the
fundamental APIs, such as the database and TLS APIs. We don't want to
have to pass logging functions to those, but they can safely use the
global logging configuration.
It appears that SOCK_NONBLOCK is not actually POSIX. According to the
OpenBSD man page, it will be soon, and according to the Linux man page,
it is a Linux extension. However, fcntl() with O_NONBLOCK seems to be
portable across both systems.
