osmo_io: Use MSG_NOSIGNAL to avoid SIGPIPE on write

Change-Id: I85433124a8e80fc2aa19b551bdaf2655ef1eea2c
diff --git a/src/core/osmo_io.c b/src/core/osmo_io.c
index f9d04fd..db1b5ad 100644
--- a/src/core/osmo_io.c
+++ b/src/core/osmo_io.c
@@ -321,7 +321,7 @@
 	if (!msghdr)
 		return -ENOMEM;
 
-	msghdr->flags = 0;
+	msghdr->flags = MSG_NOSIGNAL;
 	msghdr->iov[0].iov_base = msgb_data(msghdr->msg);
 	msghdr->iov[0].iov_len = msgb_length(msghdr->msg);
 	msghdr->hdr.msg_iov = &msghdr->iov[0];