Switch CFLAGS from -march=i586 -mtune=generic to -march=i686 -mtune=atom in Rawhide

[Nicolas Chauvet]

Hello !

FYI

The current CFLAGS for building in rawhide aren't accurate.
There is a need to move the default target from i586 to i686 :
( as reported here : https://bugzilla.rpmfusion.org/show_bug.cgi?id=760 )

Whereas noarch packages shoudn't need a rebuild , binary package will
have to be mass rebuilt once we have switched.

Nicolas (kwizart)