libzfs: fix unused, remove argsused

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

lib/libzfs/os/linux/libzfs_mount_os.c

@@ -376,6 +376,8 @@ do_mount(zfs_handle_t *zhp, const char *mntpt, char *opts, int flags)
 int
 do_unmount(zfs_handle_t *zhp, const char *mntpt, int flags)
 {
+	(void) zhp;
+
 	if (!libzfs_envvar_is_set("ZFS_MOUNT_HELPER")) {
 		int rv = umount2(mntpt, flags);
 
@@ -416,10 +418,12 @@ zfs_mount_delegation_check(void)
 void
 zpool_disable_datasets_os(zpool_handle_t *zhp, boolean_t force)
 {
+	(void) zhp, (void) force;
 }
 
 /* Called from the tail end of zfs_unmount() */
 void
 zpool_disable_volume_os(const char *name)
 {
+	(void) name;
 }

lib/libzfs/os/linux/libzfs_util_os.c

@@ -187,6 +187,7 @@ find_shares_object(differ_info_t *di)
 int
 zfs_destroy_snaps_nvl_os(libzfs_handle_t *hdl, nvlist_t *snaps)
 {
+	(void) hdl, (void) snaps;
 	return (0);
 }