Internal-linkage variables with constant-evaluatable initializers do not need to be emitted. (Also reduces the set of variables that need to be eagerly deserialized when using PCH / modules.)

llvm-svn: 245497
diff --git a/clang/test/CodeGenCXX/dllimport.cpp b/clang/test/CodeGenCXX/dllimport.cpp
index da8fb8d..c87d959 100644
--- a/clang/test/CodeGenCXX/dllimport.cpp
+++ b/clang/test/CodeGenCXX/dllimport.cpp
@@ -581,7 +581,7 @@
   constexpr KeyFuncClass() {}
   virtual void foo();
 };
-constexpr KeyFuncClass keyFuncClassVar;
+extern constexpr KeyFuncClass keyFuncClassVar = {};
 // G32-DAG: @_ZTV12KeyFuncClass = external dllimport unnamed_addr constant [3 x i8*]
 
 struct __declspec(dllimport) X : public virtual W {};