Remove bcopy(), bzero(), bcmp()

bcopy() has a confusing argument order and is actually a move, not a
copy; they're all deprecated since POSIX.1-2001 and removed in -2008,
and we shim them out to mem*() on Linux anyway

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12996

module/os/linux/zfs/zfs_dir.c

@@ -297,7 +297,7 @@ zfs_dirent_lock(zfs_dirlock_t **dlpp, znode_t *dzp, char *name,
 		 */
 		dl->dl_namesize = strlen(dl->dl_name) + 1;
 		name = kmem_alloc(dl->dl_namesize, KM_SLEEP);
-		bcopy(dl->dl_name, name, dl->dl_namesize);
+		memcpy(name, dl->dl_name, dl->dl_namesize);
 		dl->dl_name = name;
 	}
 
@@ -625,7 +625,7 @@ zfs_purgedir(znode_t *dzp)
 			skipped += 1;
 			continue;
 		}
-		bzero(&dl, sizeof (dl));
+		memset(&dl, 0, sizeof (dl));
 		dl.dl_dzp = dzp;
 		dl.dl_name = zap.za_name;