Subzero: Fix a memory leak.

src/IceConverter.h

 //===- subzero/src/IceConverter.h - Converts LLVM to ICE --------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 16 matching lines @@
 
 class Converter : public Translator {
   Converter() = delete;
   Converter(const Converter &) = delete;
   Converter &operator=(const Converter &) = delete;
 
 public:
   Converter(llvm::Module *Mod, GlobalContext *Ctx)
       : Translator(Ctx), Mod(Mod) {}
 
-  ~Converter() = default;
+  ~Converter() override = default;
 
   /// Converts the LLVM Module to ICE. Sets exit status to false if successful,
   /// true otherwise.
   void convertToIce();
 
   llvm::Module *getModule() const { return Mod; }
 
   /// Returns the global declaration associated with the corresponding
   /// global value V. If no such global address, generates fatal error.
   GlobalDeclaration *getGlobalDeclaration(const llvm::GlobalValue *V);
@@ skipping 19 matching lines @@
   /// Converts globals to ICE, and then machine code.
   void convertGlobals(llvm::Module *Mod);
 
   /// Installs global declarations into GlobalDeclarationMap.
   void installGlobalDeclarations(llvm::Module *Mod);
 };
 
 } // end of namespace ICE.
 
 #endif // SUBZERO_SRC_ICECONVERTER_H