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

Also change the pattern "foo() {}" into "foo() = default;" for ctors and dtors.

Generally avoids initializing unique_ptr<> members to nullptr in a .h file, because that requires knowing the definition of the underlying class which may not be available to all includers.

BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1197223002
diff --git a/src/IceCompileServer.h b/src/IceCompileServer.h
index ed3883b..497810a 100644
--- a/src/IceCompileServer.h
+++ b/src/IceCompileServer.h
@@ -45,7 +45,7 @@
 public:
   explicit CompileServer(Compiler &Comp) : Comp(Comp) {}
 
-  virtual ~CompileServer() {}
+  virtual ~CompileServer() = default;
 
   virtual void run() = 0;