test-stream: initialize msg.msg_flags

Coverity complains the field is not initialized.
That's true but man recvmsg specifies that this
field is set by recvmsg.

To make coverity happy, initialize this field.

Signed-off-by: Uri Lublin <uril@redhat.com>
Acked-by: Frediano Ziglio <fziglio@redhat.com>

server/tests/test-stream.c

@@ -66,6 +66,7 @@ sock_fd_read(int sock, void *buf, ssize_t bufsize, int *fd)
         msg.msg_iovlen = 1;
         msg.msg_control = cmsgu.control;
         msg.msg_controllen = sizeof(cmsgu.control);
+        msg.msg_flags = 0;
         size = recvmsg(sock, &msg, 0);
         if (size < 0) {
             perror ("recvmsg");