Keep gcc 4.x from complaining about 'lvalue required as increment operand'.
Keep gcc 4.x from complaining about 'lvalue required as increment operand'.

MohamedSeliem/contiki,bluerover/6lbr,arurke/contiki,MohamedSeliem/contiki,arurke/contiki,bluerover/6lbr,bluerover/6lbr,MohamedSeliem/contiki,arurke/contiki,arurke/contiki,arurke/contiki,bluerover/6lbr,MohamedSeliem/contiki,arurke/contiki,bluerover/6lbr,bluerover/6lbr,MohamedSeliem/contiki,bluerover/6lbr,arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki