Fix compilation failure on Windows.

This was introduced earlier but apparently used an incorrect
class name so it doesn't compile on Windows.

llvm-svn: 348176

clang-tools-extra/clangd/FSProvider.cpp

@@ -76,7 +76,7 @@ clang::clangd::RealFileSystemProvider::getFileSystem() const {
 // FIXME: Try to use a similar approach in Sema instead of relying on
 //        propagation of the 'isVolatile' flag through all layers.
 #ifdef _WIN32
-  return new VolatileFSProvider(vfs::getRealFileSystem());
+  return new VolatileFileSystem(vfs::getRealFileSystem());
 #else
   return vfs::getRealFileSystem();
 #endif