Revert "Revert "Fully support pairs in the register allocator.""

This reverts commit c399fdc442db82dfda66e6c25518872ab0f1d24f.

Change-Id: I19f8215c4b98f2f0827e04bf7806c3ca439794e5
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index 0109363..271eb82 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -1879,7 +1879,8 @@
   LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
   locations->SetInAt(1, Location::RequiresRegister());
-  locations->SetOut(Location::RequiresRegister(), true);  // The output does overlap inputs.
+  // The output does overlap inputs.
+  locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
 }
 
 void InstructionCodeGeneratorARM64::VisitInstanceOf(HInstanceOf* instruction) {