Create a typedef for HInstruction::GetInputs() return type.

And some other cleanup after
    https://android-review.googlesource.com/230742

Test: No new tests. ART test suite passed (tested on host).
Change-Id: I4743bf17544d0234c6ccb46dd0c1b9aae5c93e17
diff --git a/compiler/optimizing/bounds_check_elimination.cc b/compiler/optimizing/bounds_check_elimination.cc
index e9fcfe2..5f27e14 100644
--- a/compiler/optimizing/bounds_check_elimination.cc
+++ b/compiler/optimizing/bounds_check_elimination.cc
@@ -912,9 +912,9 @@
 
   static bool HasSameInputAtBackEdges(HPhi* phi) {
     DCHECK(phi->IsLoopHeaderPhi());
-    auto&& inputs = phi->GetInputs();
+    HConstInputsRef inputs = phi->GetInputs();
     // Start with input 1. Input 0 is from the incoming block.
-    HInstruction* input1 = inputs[1];
+    const HInstruction* input1 = inputs[1];
     DCHECK(phi->GetBlock()->GetLoopInformation()->IsBackEdge(
         *phi->GetBlock()->GetPredecessors()[1]));
     for (size_t i = 2; i < inputs.size(); ++i) {