aircrack-ng: don't build SSE code for non SSE target
Fixes:
http://autobuild.buildroot.net/results/763/7631470016f923e8f4a7696e65437c71b8668b6e/
http://autobuild.buildroot.net/results/621/621588651b5cf54726bbf5361399a2dc301b8a29/
http://autobuild.buildroot.net/results/628/628a66ef766308fba699f1faa942306e600e5575/
Cc: Laurent Cans <laurent.cans@gmail.com>
Cc: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>