pgsql: Go over all OpenSSL return values and make sure we compare them

Log Message:
-----------
Go over all OpenSSL return values and make sure we compare them
to the documented API value. The previous code got it right as
it's implemented, but accepted too much/too little compared to
the API documentation.

Per comment from Zdenek Kotala.

Modified Files:
--------------
pgsql/src/backend/libpq:
be-secure.c (r1.89 -> r1.90)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/libpq/be-secure.c?r1=1.89&r2=1.90)
pgsql/src/interfaces/libpq:
fe-secure.c (r1.118 -> r1.119)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/fe-secure.c?r1=1.118&r2=1.119)