Subzero: Use C++11 member initializers where practical.

src/IceCompiler.h

 //===- subzero/src/IceCompiler.h - Compiler driver --------------*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the driver for translating bitcode to native code.
@@ skipping 12 matching lines @@
 namespace Ice {
 
 class ClFlagsExtra;
 
 // A compiler driver. It may be called to handle a single compile request.
 class Compiler {
   Compiler(const Compiler &) = delete;
   Compiler &operator=(const Compiler &) = delete;
 
 public:
-  Compiler() {}
+  Compiler() = default;
 
   // Run the compiler with the given GlobalContext for compilation
   // state.  Upon error, the Context's error status will be set.
   void run(const ClFlagsExtra &ExtraFlags, GlobalContext &Ctx,
            std::unique_ptr<llvm::DataStreamer> &&InputStream);
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICECOMPILER_H