BUG #6663: 64bit *conn not handled properly by PQfinish

The following bug has been logged on the website:

Bug reference:      6663
Logged by:          Gilson Lasco
Email address:      gilsonlasco@yahoo.com
PostgreSQL version: 9.1.3
Operating system:   Linux Ubuntu 12.04 x64
Description:=20=20=20=20=20=20=20=20

while PQconnectdb returns addresses below 2gb, PQfinish works nicely.
First conn obj above 2gb line and PGfinish segfaults.

using libpq.a with a C multithread program