ARM64: Make the VIXL macro assembler part of ART ARM64's assembler.

This avoids a dynamic allocation of the VIXL macro assembler.

Change-Id: I4cd62678d0978f1ad6f32ea0ce7279e09152be38
diff --git a/compiler/optimizing/code_generator_arm64.h b/compiler/optimizing/code_generator_arm64.h
index 240936c..1b5fa85 100644
--- a/compiler/optimizing/code_generator_arm64.h
+++ b/compiler/optimizing/code_generator_arm64.h
@@ -243,7 +243,7 @@
   }
 
   Arm64Assembler* GetAssembler() const { return assembler_; }
-  vixl::aarch64::MacroAssembler* GetVIXLAssembler() { return GetAssembler()->vixl_masm_; }
+  vixl::aarch64::MacroAssembler* GetVIXLAssembler() { return GetAssembler()->GetVIXLAssembler(); }
 
  private:
   void GenerateClassInitializationCheck(SlowPathCodeARM64* slow_path,
@@ -364,7 +364,7 @@
  private:
   Arm64Assembler* GetAssembler() const;
   vixl::aarch64::MacroAssembler* GetVIXLAssembler() const {
-    return GetAssembler()->vixl_masm_;
+    return GetAssembler()->GetVIXLAssembler();
   }
 
   CodeGeneratorARM64* const codegen_;
@@ -413,7 +413,7 @@
   HGraphVisitor* GetInstructionVisitor() OVERRIDE { return &instruction_visitor_; }
   Arm64Assembler* GetAssembler() OVERRIDE { return &assembler_; }
   const Arm64Assembler& GetAssembler() const OVERRIDE { return assembler_; }
-  vixl::aarch64::MacroAssembler* GetVIXLAssembler() { return GetAssembler()->vixl_masm_; }
+  vixl::aarch64::MacroAssembler* GetVIXLAssembler() { return GetAssembler()->GetVIXLAssembler(); }
 
   // Emit a write barrier.
   void MarkGCCard(vixl::aarch64::Register object,