Revert "Revert r234581, it might have caused a few miscompiles in Chromium."

This reverts commit r234700.  It turns out that the lifetime markers
were not the cause of Chromium failing but a bug which was uncovered by
optimizations exposed by the markers.

llvm-svn: 235553
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index efbe07c..0d3fa07 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -1730,6 +1730,9 @@
   void EmitCXXTemporary(const CXXTemporary *Temporary, QualType TempType,
                         llvm::Value *Ptr);
 
+  llvm::Value *EmitLifetimeStart(uint64_t Size, llvm::Value *Addr);
+  void EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr);
+
   llvm::Value *EmitCXXNewExpr(const CXXNewExpr *E);
   void EmitCXXDeleteExpr(const CXXDeleteExpr *E);