libzfs: Prevent overridding of error code

zfs_send_cb_impl fails to report error for some flags.

Use second error variable for send_conclusion_record.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>
Closes openzfs#13558

lib/libzfs/libzfs_sendrecv.c

@@ -2366,9 +2366,9 @@ zfs_send_cb_impl(zfs_handle_t *zhp, const char *fromsnap, const char *tosnap,
 		 * there was some error, because it might not be totally
 		 * failed.
 		 */
-		err = send_conclusion_record(outfd, NULL);
-		if (err != 0)
-			return (zfs_standard_error(zhp->zfs_hdl, err, errbuf));
+		int err2 = send_conclusion_record(outfd, NULL);
+		if (err2 != 0)
+			return (zfs_standard_error(zhp->zfs_hdl, err2, errbuf));
 	}
 
 	return (err || sdd.err);