ReWriteStatepointsForGC: Compute base-pointer
ReWriteStatepointsForGC: Compute base-pointer

PR LLVM/#92 removes the parametrization of
RewriteStatepointsForGC phase on whether the base-pointers
of all live gc-pointers must be computed.

This change adapts LLILC code to use of new API.

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