lsl_test_internal reuseport fails on MacOS due to inability to assign ipv6 multicast address

[cboulay]

This set_option line fails

liblsl/testing/int/network.cpp

Lines 264 to 266 in e0dac29

	ip::udp::socket outsock(io_ctx, proto);
	if (addr.is_multicast())
	outsock.set_option(ip::multicast::join_group(addr));

But only for the third addrstr "ff03::1", not for the other 2.

I tried adding an error_code argument, which allows execution past that line but then fails during sendto with "no route to host". Edit: debugged in Xcode. The first error is 49 EADDRNOTAVAIL.

Assuming I can't fix this, I'd like to comment out that ff03::1 address on MacOS. It keeps causes the automated tests to fail even though it has nothing to do with recent changes. We should probably fix the underlying problem but whatever the problem is, it's already in the code and shouldn't stop our CI/CD workflows.