Make definition of CXTranslationUnitImpl private
to libclang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@119585 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index c69a97c..6b09412 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -14,6 +14,7 @@
 
 #include "CIndexer.h"
 #include "CXCursor.h"
+#include "CXTranslationUnit.h"
 #include "CXString.h"
 #include "CXType.h"
 #include "CXSourceLocation.h"