Use of IP_MULTICAST_IF makes the code not compatible with QEMU emulation

[traversaro]

In I tried to run some tests for a project that depends (transitively) on gz-transport in conda-forge/gz-sim-yarp-plugins-feedstock#14, and on linux aarch64 and ppc64le emulation using QEMU, the test fail with the following error:

Error setting socket option (IP_MULTICAST_IF).
Error setting socket option (IP_MULTICAST_IF).
Did you set the environment variable IGN_IP with a correct IP address? 
  [172.17.0.2] seems an invalid local IP address.
  Using 127.0.0.1 as hostname.
unknown file: Failure
C++ exception with description "vector::_M_range_check: __n (which is 0) >= this->size() (which is 0)" thrown in the test body.

At least the first error is expected, as the IP_MULTICAST_IF option is not supported in QEMU (see https://gitlab.com/qemu-project/qemu/-/issues/1837). I do not care too much about running tests under QEMU, but I preferred to report this so that I have a clear issue to link in the place of the script where I skip tests on QEMU.

Desired behavior

Not sure, I wanted just to report the issue to have something to reference in downstream issues.

Alternatives considered

I did not considered any alternative.

Implementation suggestion

I do not have any implementation suggestion.

Additional context