[pdb] Add unit tests for PDB MappedBlockStream and zero copy

Differential Revision: http://reviews.llvm.org/D20837
Reviewed By: ruiu

llvm-svn: 271346
diff --git a/llvm/lib/DebugInfo/PDB/Raw/ModStream.cpp b/llvm/lib/DebugInfo/PDB/Raw/ModStream.cpp
index 88c6b7c..7f59d3b 100644
--- a/llvm/lib/DebugInfo/PDB/Raw/ModStream.cpp
+++ b/llvm/lib/DebugInfo/PDB/Raw/ModStream.cpp
@@ -11,6 +11,7 @@
 
 #include "llvm/DebugInfo/CodeView/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Raw/ModInfo.h"
+#include "llvm/DebugInfo/PDB/Raw/PDBFile.h"
 #include "llvm/DebugInfo/PDB/Raw/RawError.h"
 
 using namespace llvm;