[ThinLTO] Re-commit of dot dumper after test fix

llvm-svn: 323116
diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index a36d640..69d46a5 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -388,7 +388,8 @@
       Ctx(Conf), CombinedModule(llvm::make_unique<Module>("ld-temp.o", Ctx)),
       Mover(llvm::make_unique<IRMover>(*CombinedModule)) {}
 
-LTO::ThinLTOState::ThinLTOState(ThinBackend Backend) : Backend(Backend) {
+LTO::ThinLTOState::ThinLTOState(ThinBackend Backend)
+    : Backend(Backend), CombinedIndex(/*IsPeformingAnalysis*/ false) {
   if (!Backend)
     this->Backend =
         createInProcessThinBackend(llvm::heavyweight_hardware_concurrency());