[llvm-pdbutil] Support PDBs without a DBI stream

Differential Revision: https://reviews.llvm.org/D50258

llvm-svn: 339045
diff --git a/llvm/tools/llvm-pdbutil/YAMLOutputStyle.cpp b/llvm/tools/llvm-pdbutil/YAMLOutputStyle.cpp
index a7afbf1..521e27f 100644
--- a/llvm/tools/llvm-pdbutil/YAMLOutputStyle.cpp
+++ b/llvm/tools/llvm-pdbutil/YAMLOutputStyle.cpp
@@ -191,6 +191,9 @@
   if (!opts::pdb2yaml::DbiStream)
     return Error::success();
 
+  if (!File.hasPDBDbiStream())
+    return Error::success();
+
   auto DbiS = File.getPDBDbiStream();
   if (!DbiS)
     return DbiS.takeError();