cp-profiler never sends "done" message

[StefanBruens]

Describe the bug

The profiler should send a "START" message, n "NODE" messages, and a "DONE" message. The START and NODE messages are send, but the DONE is omitted

To Reproduce

netcat -l 1234 > /tmp/cpprofiler.out
/usr/bin/minizinc --solver gecode --json-stream  01_sevenpaces/models/cuhkmelb.mzn  --cp-profiler -723467520,1234

https://github.com/Gecode/gecode/blob/027c57889d66dd26ad8e1a419c2cda22ab0cf305/gecode/search/cpprofiler/tracer.cpp#L147-L150

There is probably a connector->done() missing.

https://github.com/Gecode/gecode/blob/fec7e9fd99bca98f146416ba8ea8adc278f5a95a/gecode/search/cpprofiler/connector.hpp#L373-L377

Gecode and Platform Configuration

Gecode 6.3.0 branch (2022-04-30)