Fix Windows-specific race condition in syslogger. This could've been

Fix Windows-specific race condition in syslogger. This could've been
the cause of the "could not write to log file: Bad file descriptor"
errors reported at
http://archives.postgresql.org//pgsql-general/2008-06/msg00193.php

Backpatch to 8.3, the race condition was introduced by the CSV logging
patch.

Analysis and patch by Gurjeet Singh.