Move pdb code into pdb namespace.

llvm-svn: 268544
diff --git a/llvm/lib/DebugInfo/PDB/PDBSymbol.cpp b/llvm/lib/DebugInfo/PDB/PDBSymbol.cpp
index 9d83181..78b3afc 100644
--- a/llvm/lib/DebugInfo/PDB/PDBSymbol.cpp
+++ b/llvm/lib/DebugInfo/PDB/PDBSymbol.cpp
@@ -50,6 +50,7 @@
 #include <utility>
 
 using namespace llvm;
+using namespace llvm::pdb;
 
 PDBSymbol::PDBSymbol(const IPDBSession &PDBSession,
                      std::unique_ptr<IPDBRawSymbol> Symbol)