Clean up JNI calling convention callee saves.

Precalculate callee saves at compile time and return them
as ArrayRef<> instead of keeping then in a std::vector<>.

Change-Id: I4fd7d2bbf6138dc31b0fe8554eac35b0777ec9ef
diff --git a/compiler/utils/arm64/assembler_arm64.h b/compiler/utils/arm64/assembler_arm64.h
index c4e5de7..91171a8 100644
--- a/compiler/utils/arm64/assembler_arm64.h
+++ b/compiler/utils/arm64/assembler_arm64.h
@@ -109,12 +109,13 @@
   void UnspillRegisters(vixl::CPURegList registers, int offset);
 
   // Emit code that will create an activation on the stack.
-  void BuildFrame(size_t frame_size, ManagedRegister method_reg,
-                  const std::vector<ManagedRegister>& callee_save_regs,
+  void BuildFrame(size_t frame_size,
+                  ManagedRegister method_reg,
+                  ArrayRef<const ManagedRegister> callee_save_regs,
                   const ManagedRegisterEntrySpills& entry_spills) OVERRIDE;
 
   // Emit code that will remove an activation from the stack.
-  void RemoveFrame(size_t frame_size, const std::vector<ManagedRegister>& callee_save_regs)
+  void RemoveFrame(size_t frame_size, ArrayRef<const ManagedRegister> callee_save_regs)
       OVERRIDE;
 
   void IncreaseFrameSize(size_t adjust) OVERRIDE;