pgsql: Define LDAPS_PORT if it's missing and disable implicit LDAPSon

Define LDAPS_PORT if it's missing and disable implicit LDAPS on Windows

Some versions of Windows don't define LDAPS_PORT.

Also, Windows' ldap_sslinit() is documented to use LDAPS even if you
said secure=0 when the port number happens to be 636 or 3269.  Let's
avoid using the port number to imply that you want LDAPS, so that
connection strings have the same meaning on Windows and Unix.

Author: Thomas Munro
Discussion: https://postgr.es/m/CAEepm%3D23B7GV4AUz3MYH1TKpTv030VHxD2Sn%2BLYWDv8d-qWxww%40mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/3ad2afc2e98fc85d5cf9529d84265b70acc0b13d

Modified Files
--------------
src/backend/libpq/auth.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)