Fix break of runtime on Linux
Fix break of runtime on Linux

Recent checkin that moved PalDebugBreak implementation from
PalRedhawk.h to PalRedhawkMinWin.cpp has broken Linux PAL, since
it needs to be in PalRedhawkUnix.cpp as well. So I am adding that.
Also removing one function that was just a helper and use the
implementation in platform.linux.cpp instead.

manu-silicon/corert,mjp41/corert,schellap/corert,botaberg/corert,botaberg/corert,gregkalapos/corert,tijoytom/corert,tijoytom/corert,krytarowski/corert,mjp41/corert,gregkalapos/corert,yizhang82/corert,gregkalapos/corert,manu-silicon/corert,shrah/corert,yizhang82/corert,sandreenko/corert,botaberg/corert,shrah/corert,kyulee1/corert,mjp41/corert,mjp41/corert,krytarowski/corert,krytarowski/corert,kyulee1/corert,schellap/corert,gregkalapos/corert,manu-silicon/corert,tijoytom/corert,schellap/corert,manu-silicon/corert,sandreenko/corert,schellap/corert,krytarowski/corert,schellap/corert,shrah/corert,botaberg/corert,shrah/corert,sandreenko/corert,mjp41/corert,yizhang82/corert,manu-silicon/corert,tijoytom/corert,yizhang82/corert,kyulee1/corert,kyulee1/corert,sandreenko/corert