Update clang to r339409.

Change-Id: I800772d2d838223be1f6b40d490c4591b937fca2
diff --git a/linux-x64/clang/include/llvm/DebugInfo/MSF/MSFBuilder.h b/linux-x64/clang/include/llvm/DebugInfo/MSF/MSFBuilder.h
index 19e5c31..3de98c4 100644
--- a/linux-x64/clang/include/llvm/DebugInfo/MSF/MSFBuilder.h
+++ b/linux-x64/clang/include/llvm/DebugInfo/MSF/MSFBuilder.h
@@ -20,11 +20,13 @@
 #include <vector>
 
 namespace llvm {
+class FileBufferByteStream;
+class WritableBinaryStream;
 namespace msf {
 
 class MSFBuilder {
 public:
-  /// \brief Create a new `MSFBuilder`.
+  /// Create a new `MSFBuilder`.
   ///
   /// \param BlockSize The internal block size used by the PDB file.  See
   /// isValidBlockSize() for a list of valid block sizes.
@@ -109,7 +111,10 @@
 
   /// Finalize the layout and build the headers and structures that describe the
   /// MSF layout and can be written directly to the MSF file.
-  Expected<MSFLayout> build();
+  Expected<MSFLayout> generateLayout();
+
+  /// Write the MSF layout to the underlying file.
+  Expected<FileBufferByteStream> commit(StringRef Path, MSFLayout &Layout);
 
   BumpPtrAllocator &getAllocator() { return Allocator; }