Update for LLVM api change.

llvm-svn: 216585
diff --git a/clang/unittests/Basic/VirtualFileSystemTest.cpp b/clang/unittests/Basic/VirtualFileSystemTest.cpp
index 39febca..bdd4373 100644
--- a/clang/unittests/Basic/VirtualFileSystemTest.cpp
+++ b/clang/unittests/Basic/VirtualFileSystemTest.cpp
@@ -539,7 +539,7 @@
   IntrusiveRefCntPtr<vfs::FileSystem>
   getFromYAMLRawString(StringRef Content,
                        IntrusiveRefCntPtr<vfs::FileSystem> ExternalFS) {
-    std::unique_ptr<MemoryBuffer> Buffer(MemoryBuffer::getMemBuffer(Content));
+    std::unique_ptr<MemoryBuffer> Buffer = MemoryBuffer::getMemBuffer(Content);
     return getVFSFromYAML(std::move(Buffer), CountingDiagHandler, this,
                           ExternalFS);
   }