Added configuration option to circumvent C compilers that have problems with const function pointers (i.e., sdcc)
Added configuration option to circumvent C compilers that have problems with const function pointers (i.e., sdcc)

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