[LTP] tst_atomic: add atomic_add_return for ARC

[Jan Stancek]

----- Original Message -----
> From: "Vineet Gupta" <Vineet.Gupta1@synopsys.com>
> To: ltp@lists.linux.it
> Cc: "Vineet Gupta" <Vineet.Gupta1@synopsys.com>, linux-snps-arc@lists.infreadead.org
> Sent: Thursday, 1 September, 2016 1:39:48 AM
> Subject: [LTP]  tst_atomic: add atomic_add_return for ARC
> 
> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

Pushed.

Thanks,
Jan