[llvm-pdbdump] Dump File / Line Info to YAML.

We were already parsing and dumping this to the human readable
format, but not to the YAML format.  This does so, in preparation
for reading it in and reconstructing the line information from
YAML.

llvm-svn: 301357
diff --git a/llvm/lib/DebugInfo/PDB/Native/ModStream.cpp b/llvm/lib/DebugInfo/PDB/Native/ModStream.cpp
index 08798cf..e87e2c4 100644
--- a/llvm/lib/DebugInfo/PDB/Native/ModStream.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/ModStream.cpp
@@ -82,4 +82,8 @@
   return make_range(LineInfo.begin(HadError), LineInfo.end());
 }
 
+bool ModStream::hasLineInfo() const {
+  return C13LinesSubstream.getLength() > 0 || LinesSubstream.getLength() > 0;
+}
+
 Error ModStream::commit() { return Error::success(); }