src: Return on UV_ENOSYS in GetInterfaceAddresses.

When using SUNOS_NO_IFADDRS (on Solaris 10, for context) libuv returns -ENOSYS.

When that error is seen this method sets the response to the error code, but continues processing.

This leads to a segfault in uv_free_interface_addresses. Instead, just return as there is no need to process the rest of the function (afaict?)