pgsql: Fix ALTER LARGE OBJECT and GRANT ...

Log Message:
-----------
Fix ALTER LARGE OBJECT and GRANT ... ON LARGE OBJECT for large OIDs.

The previous coding failed for OIDs too large to be represented by
a signed integer.

Modified Files:
--------------
    pgsql/src/backend/catalog:
        aclchk.c (r1.166 -> r1.167)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/aclchk.c?r1=1.166&r2=1.167)
    pgsql/src/backend/commands:
        alter.c (r1.35 -> r1.36)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/alter.c?r1=1.35&r2=1.36)
        comment.c (r1.114 -> r1.115)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/comment.c?r1=1.114&r2=1.115)
    pgsql/src/backend/parser:
        gram.y (r2.712 -> r2.713)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y?r1=2.712&r2=2.713)
    pgsql/src/backend/utils/adt:
        oid.c (r1.76 -> r1.77)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/oid.c?r1=1.76&r2=1.77)
    pgsql/src/include/utils:
        builtins.h (r1.348 -> r1.349)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/builtins.h?r1=1.348&r2=1.349)