Update for llvm API change.

llvm-svn: 216576
diff --git a/clang/lib/Basic/VirtualFileSystem.cpp b/clang/lib/Basic/VirtualFileSystem.cpp
index 0db8d31..df446bb 100644
--- a/clang/lib/Basic/VirtualFileSystem.cpp
+++ b/clang/lib/Basic/VirtualFileSystem.cpp
@@ -869,7 +869,7 @@
                                  IntrusiveRefCntPtr<FileSystem> ExternalFS) {
 
   SourceMgr SM;
-  yaml::Stream Stream(std::move(Buffer), SM);
+  yaml::Stream Stream(Buffer->getMemBufferRef(), SM);
 
   SM.setDiagHandler(DiagHandler, DiagContext);
   yaml::document_iterator DI = Stream.begin();