Make gcc default LD, and allow override with LD_OVERRIDE
Make gcc default LD, and allow override with LD_OVERRIDE

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