[C++] Use 'nullptr'. Target edition.

llvm-svn: 207197
diff --git a/llvm/lib/Target/CppBackend/CPPBackend.cpp b/llvm/lib/Target/CppBackend/CPPBackend.cpp
index afd1f51..f16547a 100644
--- a/llvm/lib/Target/CppBackend/CPPBackend.cpp
+++ b/llvm/lib/Target/CppBackend/CPPBackend.cpp
@@ -396,7 +396,7 @@
     return I->second;
 
   // Okay, let's build a new name for this type. Start with a prefix
-  const char* prefix = 0;
+  const char* prefix = nullptr;
   switch (Ty->getTypeID()) {
   case Type::FunctionTyID:    prefix = "FuncTy_"; break;
   case Type::StructTyID:      prefix = "StructTy_"; break;