topology: add On commit to the temporary tables

[aperi2007]

In the trunk/topology/topology.sql.in.c

I think would be good to add "ON COMMIT DROP" to the create TEMP Tables. So it would be dropped on exit from function.

I don't know if this is available in early versions of postgres.

[strk]

Fixed by r6668

[strk]

for the record, "ON COMMIT DROP" is surely available as of 8.3, which is the minimum requirement for postgis nowadays.