Automatically convert SRID<0 to SRID=0 in topology.topology

[strk]

I just found that the topology built by the testsuite (load_topology.sql) succeeds in writing a -1 value in topology.topology.srid field.

This, in turn, can confuse clients: ​http://hub.qgis.org/issues/12802

As we gently convert -1 to 0 in other cases, I think it would be nice to do it also in the topology.topology.srid case.

Since people might already have -1's in their db, part of this would be converting existing values, updating the table.

[robe]

Milestone renamed

[Sandro Santilli <strk@…>]

In e5054a9/git:

Update topology.topology srids < 0 on upgrade

Closes #3192

[strk]

For the record: [fba0330289c7ad2ed3cc5642f259940c59beda6b/git] made CreateTopology convert SRID<0 to 0