du: don't count duplicate arguments. Closes 5288

du: don't count duplicate arguments. Closes 5288

Since coreutils 8.6 (2010-10-15) du no longer counts duplicate arguments.

Revert the relevant part of commit 618a3027ed (du: fix "du /dir /dir"
case).

function                                             old     new   delta
du_main                                              302     297      -5
reset_ino_dev_hashtable                               78       -     -78
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 0/1 up/down: 0/-83)             Total: -83 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>