A couple of fixes for using Makefile.standalone on Mac.

src/IceTargetLowering.h

Index: src/IceTargetLowering.h
diff --git a/src/IceTargetLowering.h b/src/IceTargetLowering.h
index c79894394704d67af2b24450b74069341f26de05..da52adfcc7ae838a8781085a8cd2954d9d48823e 100644
--- a/src/IceTargetLowering.h
+++ b/src/IceTargetLowering.h
@@ -211,6 +211,8 @@ class TargetGlobalInitLowering {
 public:
   static TargetGlobalInitLowering *createLowering(TargetArch Target,
                                                   GlobalContext *Ctx);
+  virtual ~TargetGlobalInitLowering();
+
   // TODO: Allow relocations to be represented as part of the Data.
   virtual void lower(const IceString &Name, SizeT Align, bool IsInternal,
                      bool IsConst, bool IsZeroInitializer, SizeT Size,