[SofaBaseTopology] FIX wrong clean in PointSetTopologyModifier

[guparan]

Quick commit to fix build error after #370 merge.

---

This PR:

• builds with SUCCESS for all platforms on the CI.
• does not generate new warnings.
• does not generate new unit test failures.
• does not generate new scene test failures.
• does not break API compatibility.
• is more than 1 week old (or has fast-merge label).

Reviewers will merge only if all these checks are true.

[damienmarchal]

Thank you Guillaume,
I vote for fast-merge.

But i think it is better to chain the two message like that:

msg_info() << "Blahblah" << msgendl
                  << "Other thing";

Because it faster and if the two line are forming a single message it is more clear to have that:

INFO (MyComponent) : "Blahblah" 
                                       "OtherThing"

Instead of:

INFO (MyComponent) : "Blahblah"
INFO (MyComponent) : "OtherThing"

[damienmarchal]

Ok...but I think it is better to chaing the two message in a single dmsg_info(). I give an example in the comments.

[guparan]

Agree, was just missing msgendl existence ;-)