[clang-rename] Fix some Clang-tidy modernize-use-override and Include What You Use warnings; other minor fixes

[omtcyfz]

LGTM

clang-rename/USRFinder.h

 //===--- tools/extra/clang-rename/USRFinder.h - Clang rename tool ---------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// \brief Methods for determining the USR of a symbol at a location in source
 /// code.
 ///
 //===----------------------------------------------------------------------===//
+
 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_RENAME_USR_FINDER_H
 #define LLVM_CLANG_TOOLS_EXTRA_CLANG_RENAME_USR_FINDER_H
 
 #include "clang/AST/AST.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/ASTMatchers/ASTMatchFinder.h"
 #include <string>
+#include <vector>
 
 using namespace llvm;
 using namespace clang::ast_matchers;
 
 namespace clang {
+
 class ASTContext;
 class Decl;
 class SourceLocation;
 class NamedDecl;
 
 namespace rename {
 
 // Given an AST context and a point, returns a NamedDecl identifying the symbol

 
 private:
   void addMatchers() {
     const auto NestedNameSpecifierLocMatcher =
         nestedNameSpecifierLoc().bind("nestedNameSpecifierLoc");
     Finder.addMatcher(NestedNameSpecifierLocMatcher, this);
   }
 
-  virtual void run(const MatchFinder::MatchResult &Result) {
+  void run(const MatchFinder::MatchResult &Result) override {
     const auto *NNS = Result.Nodes.getNodeAs<NestedNameSpecifierLoc>(
         "nestedNameSpecifierLoc");
     Locations.push_back(*NNS);
   }
 
   ASTContext &Context;
   std::vector<NestedNameSpecifierLoc> Locations;
   MatchFinder Finder;
 };
-}
-}
+
+} // namespace rename
+} // namespace clang
 
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_RENAME_USR_FINDER_H