Add a few Subzero intrinsics (not the atomic ones yet).

src/IceTargetLowering.h

Index: src/IceTargetLowering.h
diff --git a/src/IceTargetLowering.h b/src/IceTargetLowering.h
index 7f798a89d62ab46fb2a828cd5cee5021c4f1d9db..dbb9a428222ca3ee4479e7985c6c61c2224145cf 100644
--- a/src/IceTargetLowering.h
+++ b/src/IceTargetLowering.h
@@ -167,6 +167,7 @@ protected:
   virtual void lowerCast(const InstCast *Inst) = 0;
   virtual void lowerFcmp(const InstFcmp *Inst) = 0;
   virtual void lowerIcmp(const InstIcmp *Inst) = 0;
+  virtual void lowerIntrinsicCall(const InstIntrinsicCall *Inst) = 0;
   virtual void lowerLoad(const InstLoad *Inst) = 0;
   virtual void lowerPhi(const InstPhi *Inst) = 0;
   virtual void lowerRet(const InstRet *Inst) = 0;