[tidy] Check modernize-use-auto

Ref: http://clang.llvm.org/extra/clang-tidy/checks/modernize-use-auto.html

test/util/thread_local.cpp

@@ -80,8 +80,8 @@ TEST(ThreadLocalStorage, AutoReclaim) {
 
     unsigned counter = 0;
 
-    DtorCounter* dtorCounter1 = new DtorCounter{ &counter };
-    DtorCounter* dtorCounter2 = new DtorCounter{ &counter };
+    auto dtorCounter1 = new DtorCounter{ &counter };
+    auto dtorCounter2 = new DtorCounter{ &counter };
 
     ThreadContext context = {"Test"};