Revert "Fully support pairs in the register allocator."

Libcore tests fail.

This reverts commit 41aedbb684ccef76ff8373f39aba606ce4cb3194.

Change-Id: I2572f120d4bbaeb7a4d4cbfd47ab00c9ea39ac6c
diff --git a/compiler/optimizing/code_generator_arm64.cc b/compiler/optimizing/code_generator_arm64.cc
index 7dfb69f..306845b 100644
--- a/compiler/optimizing/code_generator_arm64.cc
+++ b/compiler/optimizing/code_generator_arm64.cc
@@ -1863,8 +1863,7 @@
   LocationSummary* locations = new (GetGraph()->GetArena()) LocationSummary(instruction, call_kind);
   locations->SetInAt(0, Location::RequiresRegister());
   locations->SetInAt(1, Location::RequiresRegister());
-  // The output does overlap inputs.
-  locations->SetOut(Location::RequiresRegister(), Location::kOutputOverlap);
+  locations->SetOut(Location::RequiresRegister(), true);  // The output does overlap inputs.
 }
 
 void InstructionCodeGeneratorARM64::VisitInstanceOf(HInstanceOf* instruction) {