ART: Fix linting errors

Fix bounds_check_elimination linting errors.

Change-Id: I040433ecbc84d740bff331c37df0bfcc64dc244e
diff --git a/compiler/optimizing/bounds_check_elimination.cc b/compiler/optimizing/bounds_check_elimination.cc
index 91455bc..c353d66 100644
--- a/compiler/optimizing/bounds_check_elimination.cc
+++ b/compiler/optimizing/bounds_check_elimination.cc
@@ -384,7 +384,7 @@
 
 class BCEVisitor : public HGraphVisitor {
  public:
-  BCEVisitor(HGraph* graph)
+  explicit BCEVisitor(HGraph* graph)
       : HGraphVisitor(graph),
         maps_(graph->GetBlocks().Size()) {}
 
@@ -575,7 +575,7 @@
 
   void VisitPhi(HPhi* phi) {
     if (phi->IsLoopHeaderPhi() && phi->GetType() == Primitive::kPrimInt) {
-      DCHECK(phi->InputCount() == 2);
+      DCHECK_EQ(phi->InputCount(), 2U);
       HInstruction* instruction = phi->InputAt(1);
       if (instruction->IsAdd()) {
         HAdd* add = instruction->AsAdd();