Add some std::move where the value is only read otherwise.

This mostly affects smart pointers. No functionality change intended.

llvm-svn: 272520
diff --git a/clang/lib/Basic/VirtualFileSystem.cpp b/clang/lib/Basic/VirtualFileSystem.cpp
index d64c4e3..2eb7a84 100644
--- a/clang/lib/Basic/VirtualFileSystem.cpp
+++ b/clang/lib/Basic/VirtualFileSystem.cpp
@@ -280,7 +280,7 @@
 // OverlayFileSystem implementation
 //===-----------------------------------------------------------------------===/
 OverlayFileSystem::OverlayFileSystem(IntrusiveRefCntPtr<FileSystem> BaseFS) {
-  FSList.push_back(BaseFS);
+  FSList.push_back(std::move(BaseFS));
 }
 
 void OverlayFileSystem::pushOverlay(IntrusiveRefCntPtr<FileSystem> FS) {
@@ -1395,7 +1395,7 @@
   RedirectingFileSystemParser P(Stream);
 
   std::unique_ptr<RedirectingFileSystem> FS(
-      new RedirectingFileSystem(ExternalFS));
+      new RedirectingFileSystem(std::move(ExternalFS)));
 
   if (!YAMLFilePath.empty()) {
     // Use the YAML path from -ivfsoverlay to compute the dir to be prefixed
@@ -1576,7 +1576,8 @@
                     void *DiagContext,
                     IntrusiveRefCntPtr<FileSystem> ExternalFS) {
   return RedirectingFileSystem::create(std::move(Buffer), DiagHandler,
-                                       YAMLFilePath, DiagContext, ExternalFS);
+                                       YAMLFilePath, DiagContext,
+                                       std::move(ExternalFS));
 }
 
 UniqueID vfs::getNextVirtualUniqueID() {