[DebugInfo/PDB] Adding getUndecoratedNameEx and IPDB interfaces for IDiaEnumTables and IDiaTable.

Initial changes to support debugging PE/COFF files with LLDB on Windows through DIA SDK.
There is another set of changes required on the LLDB side before this does anything.

Differential Revision: https://reviews.llvm.org/D39517

llvm-svn: 318403
diff --git a/llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp b/llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp
index 7be4c76..b01c2b5 100644
--- a/llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp
@@ -245,3 +245,7 @@
 std::unique_ptr<IPDBEnumDataStreams> NativeSession::getDebugStreams() const {
   return nullptr;
 }
+
+std::unique_ptr<IPDBEnumTables> NativeSession::getEnumTables() const {
+  return nullptr;
+}