[PATCH] initialize pgconn to null

This patch fixes a potential segfault that can happen if a dbc handle is created and then destroyed without attempting
aconnection. 

The problem is that CC_Constructor doesn't initialize this new member variable.

--- connection.c.old    2005-10-24 21:23:55.000000000 -0400
+++ connection.c        2005-10-24 21:16:39.000000000 -0400
@@ -2443,6 +2443,7 @@
                rv->current_schema = NULL;
                rv->num_discardp = 0;
                rv->discardp = NULL;
+                rv->pgconn = NULL;

                /* Initialize statement options to defaults */
                /* Statements under this conn will inherit these options */