pgsql: Use STDOUT/STDERR_FILENO in most of syslogger.

Use STDOUT/STDERR_FILENO in most of syslogger.

This fixes problems on windows when logging collector is used in a service,
failing with:
FATAL:  could not redirect stderr: Bad file descriptor

This is triggered by 76e38b37a5. The problem is that STDOUT/STDERR_FILENO
aren't defined on windows, which lead us to use _fileno(stdout) etc, but that
doesn't work if stdout/stderr are closed.

Author: Andres Freund <andres@anarazel.de>
Reported-By: Sandeep Thakkar <sandeep.thakkar@enterprisedb.com>
Message-Id: 20220520164558.ozb7lm6unakqzezi@alap3.anarazel.de (on pgsql-packagers)
Backpatch: 15-, where 76e38b37a5 came in

Branch
------
REL_15_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/c91a216ef7385e78e7eb80355c4d02953711bdba

Modified Files
--------------
src/backend/postmaster/syslogger.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)