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.h b/compiler/optimizing/dead_code_elimination.h
index 58e700d..84fd890 100644
--- a/compiler/optimizing/dead_code_elimination.h
+++ b/compiler/optimizing/dead_code_elimination.h
@@ -29,9 +29,7 @@
  */
 class HDeadCodeElimination : public HOptimization {
  public:
-  HDeadCodeElimination(HGraph* graph,
-                       OptimizingCompilerStats* stats = nullptr,
-                       const char* name = kDeadCodeEliminationPassName)
+  HDeadCodeElimination(HGraph* graph, OptimizingCompilerStats* stats, const char* name)
       : HOptimization(graph, name, stats) {}
 
   void Run() OVERRIDE;