ART: Fix tidy warnings

Switch to char versions of find variants.

Add "explicit" constructor variants or refactor and
remove defaults.

Use const references.

Bug: 32619234
Test: m test-art-host
Change-Id: I970cc2f47d6cf8f0c74104b994b075b2fafb3d45
diff --git a/compiler/optimizing/dead_code_elimination_test.cc b/compiler/optimizing/dead_code_elimination_test.cc
index fe52aac..fdd77e7 100644
--- a/compiler/optimizing/dead_code_elimination_test.cc
+++ b/compiler/optimizing/dead_code_elimination_test.cc
@@ -44,7 +44,7 @@
   std::unique_ptr<const X86InstructionSetFeatures> features_x86(
       X86InstructionSetFeatures::FromCppDefines());
   x86::CodeGeneratorX86 codegenX86(graph, *features_x86.get(), CompilerOptions());
-  HDeadCodeElimination(graph).Run();
+  HDeadCodeElimination(graph, nullptr /* stats */, "dead_code_elimination").Run();
   GraphChecker graph_checker(graph);
   graph_checker.Run();
   ASSERT_TRUE(graph_checker.IsValid());