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/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index a484760..6f84cdc 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -758,7 +758,7 @@
       graph, stats, "dead_code_elimination$after_inlining");
   HDeadCodeElimination* dce3 = new (arena) HDeadCodeElimination(
       graph, stats, "dead_code_elimination$final");
-  HConstantFolding* fold1 = new (arena) HConstantFolding(graph);
+  HConstantFolding* fold1 = new (arena) HConstantFolding(graph, "constant_folding");
   InstructionSimplifier* simplify1 = new (arena) InstructionSimplifier(graph, stats);
   HSelectGenerator* select_generator = new (arena) HSelectGenerator(graph, stats);
   HConstantFolding* fold2 = new (arena) HConstantFolding(