libshare: nfs: fix unused, remove argsused

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12844

lib/libshare/nfs.c

@@ -249,6 +249,8 @@ fullerr:
 static boolean_t
 nfs_is_shared_cb(void *userdata, char *line, boolean_t found_mountpoint)
 {
+	(void) line;
+
 	boolean_t *found = userdata;
 	*found = found_mountpoint;
 	return (!found_mountpoint);