[clang-rename] Respect the traversal scope when traversing the entire AST.

Summary:
This should be NFC to clang-rename, by default the traversal scope is
TUDecl. Traversing the TUDecl in clangd is a performance cliff, we should
avoid it.

Reviewers: ilya-biryukov

Subscribers: kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69892

Author: hokein

clang/lib/Tooling/Refactoring/Rename/USRFindingAction.cpp

@@ -67,7 +67,7 @@ class AdditionalUSRFinder : public RecursiveASTVisitor<AdditionalUSRFinder> {
 
   std::vector<std::string> Find() {
     // Fill OverriddenMethods and PartialSpecs storages.
-    TraverseDecl(Context.getTranslationUnitDecl());
+    TraverseAST(Context);
     if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(FoundDecl)) {
       addUSRsOfOverridenFunctions(MethodDecl);
       for (const auto &OverriddenMethod : OverriddenMethods) {