tests/qtest/netdev-socket: Do not test multicast on Darwin

Do not run this test on Darwin, otherwise we get:

  qemu-system-arm: -netdev dgram,id=st0,remote.type=inet,remote.host=230.0.0.1,remote.port=1234:
   can't add socket to multicast group 230.0.0.1: Can't assign requested address
  Broken pipe
  ../../tests/qtest/libqtest.c:191: kill_qemu() tried to terminate QEMU
   process but encountered exit status 1 (expected 0)
  Abort trap: 6

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20230918062549.2363-1-philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/qtest/netdev-socket.c

@@ -401,7 +401,7 @@ static void test_dgram_inet(void)
     qtest_quit(qts0);
 }
 
-#ifndef _WIN32
+#if !defined(_WIN32) && !defined(CONFIG_DARWIN)
 static void test_dgram_mcast(void)
 {
     QTestState *qts;
@@ -414,7 +414,9 @@ static void test_dgram_mcast(void)
 
     qtest_quit(qts);
 }
+#endif
 
+#ifndef _WIN32
 static void test_dgram_unix(void)
 {
     QTestState *qts0, *qts1;
@@ -511,7 +513,7 @@ int main(int argc, char **argv)
     if (has_ipv4) {
         qtest_add_func("/netdev/stream/inet/ipv4", test_stream_inet_ipv4);
         qtest_add_func("/netdev/dgram/inet", test_dgram_inet);
-#ifndef _WIN32
+#if !defined(_WIN32) && !defined(CONFIG_DARWIN)
         qtest_add_func("/netdev/dgram/mcast", test_dgram_mcast);
 #endif
     }