pgsql: Minor code cleanup: remove a variable that was assigned to but

Log Message:
-----------
Minor code cleanup: remove a variable that was assigned to but never
subsequently referenced.

Found by: Coverity
Fixed by: Sean Chittenden

Modified Files:
--------------
pgsql/src/backend/catalog:
pg_largeobject.c (r1.22 -> r1.23)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/pg_largeobject.c.diff?r1=1.22&r2=1.23)