Correctly initialize Reader to null.

llvm-svn: 107994
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index fa5338d..5037c83 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -37,7 +37,7 @@
 using namespace clang;
 
 CompilerInstance::CompilerInstance()
-  : Invocation(new CompilerInvocation()) {
+  : Invocation(new CompilerInvocation()), Reader(0) {
 }
 
 CompilerInstance::~CompilerInstance() {