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/pc_relative_fixups_x86.cc b/compiler/optimizing/pc_relative_fixups_x86.cc
index 93116f8..921f3df 100644
--- a/compiler/optimizing/pc_relative_fixups_x86.cc
+++ b/compiler/optimizing/pc_relative_fixups_x86.cc
@@ -211,7 +211,7 @@
     }
 
     // Ensure that we can load FP arguments from the constant area.
-    auto&& inputs = invoke->GetInputs();
+    HInputsRef inputs = invoke->GetInputs();
     for (size_t i = 0; i < inputs.size(); i++) {
       HConstant* input = inputs[i]->AsConstant();
       if (input != nullptr && Primitive::IsFloatingPointType(input->GetType())) {