Small clangd cleanups, NFC

 - remove old ASTUnit includes
 - fix typo (regiterCallbackHandlers)

llvm-svn: 314532
diff --git a/clang-tools-extra/clangd/ProtocolHandlers.cpp b/clang-tools-extra/clangd/ProtocolHandlers.cpp
index 066a995..544c44c 100644
--- a/clang-tools-extra/clangd/ProtocolHandlers.cpp
+++ b/clang-tools-extra/clangd/ProtocolHandlers.cpp
@@ -228,7 +228,7 @@
 
 } // namespace
 
-void clangd::regiterCallbackHandlers(JSONRPCDispatcher &Dispatcher,
+void clangd::registerCallbackHandlers(JSONRPCDispatcher &Dispatcher,
                                      JSONOutput &Out,
                                      ProtocolCallbacks &Callbacks) {
   Dispatcher.registerHandler(