pgsql: Rearrange order of pre-commit operations: must close cursors

Log Message:
-----------
Rearrange order of pre-commit operations: must close cursors before doing
ON COMMIT actions. Per bug report from Michael Guerin.

Modified Files:
--------------
pgsql/src/backend/access/transam:
xact.c (r1.192 -> r1.193)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xact.c.diff?r1=1.192&r2=1.193)