Set correct context for new IR in readerPostVisit
Set correct context for new IR in readerPostVisit

Make sure that CurrentInstrOffset and CurrentRegion have reasonable values
when inserting prolog code after parsing all instructions (previously they
were inadvertently getting the end-of-function values).

adiaaida/llilc,kyulee1/llilcjit,BruceForstall/llilc,russellhadley/llilc,JosephTremoulet/llilc,adiaaida/llilc,AndyAyersMS/llilc,dotnet/llilc,dotnet/llilc,russellhadley/llilc,swaroop-sridhar/llilc,marksantos/llilc,AndyAyersMS/llilc,BruceForstall/llilc,manu-silicon/llilc,manu-silicon/llilc,marksantos/llilc,swaroop-sridhar/llilc,adiaaida/llilc,JosephTremoulet/llilc,swaroop-sridhar/llilc,dotnet/llilc,kyulee1/llilcjit,marksantos/llilc,russellhadley/llilc,kyulee1/llilcjit,BruceForstall/llilc,AndyAyersMS/llilc,manu-silicon/llilc,JosephTremoulet/llilc