pgsql: Disallow empty passwords in LDAP authentication, the same way we

Log Message:
-----------
Disallow empty passwords in LDAP authentication, the same way
we already do it for PAM.

Modified Files:
--------------
pgsql/src/backend/libpq:
auth.c (r1.182 -> r1.183)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/auth.c?r1=1.182&r2=1.183)