[DebugInfo] Add a new method IPDBSession::findLineNumbersBySectOffset

Summary:
Some PDB symbols do not have a valid VA or RVA but have Addr by Section and Offset. For example, a variable in thread-local storage has the following properties:

     get_addressOffset: 0
     get_addressSection: 5
     get_lexicalParentId: 2
     get_name: g_tls
     get_symIndexId: 12
     get_typeId: 4
     get_dataKind: 6
     get_symTag: 7
     get_locationType: 2

This change provides a new method to locate line numbers by Section and Offset from those symbols.

Reviewers: zturner, rnk, llvm-commits

Subscribers: asmith, JDevlieghere

Differential Revision: https://reviews.llvm.org/D44407

llvm-svn: 327601
diff --git a/llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp b/llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp
index 481eb77..c4d188ee 100644
--- a/llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/NativeSession.cpp
@@ -202,6 +202,12 @@
   return nullptr;
 }
 
+std::unique_ptr<IPDBEnumLineNumbers>
+NativeSession::findLineNumbersBySectOffset(uint32_t Section, uint32_t Offset,
+                                           uint32_t Length) const {
+  return nullptr;
+}
+
 std::unique_ptr<IPDBEnumSourceFiles>
 NativeSession::findSourceFiles(const PDBSymbolCompiland *Compiland,
                                StringRef Pattern,