Factorize code for common LocationSummary of HInvoke.

This is one step forward, we could factorize more, but
I wanted to get this out of the way first.

Change-Id: I6ae411a737eebaecb64974f47af507ce0cfbae85
diff --git a/compiler/optimizing/code_generator_arm64.h b/compiler/optimizing/code_generator_arm64.h
index 7a502e0..c62ba95 100644
--- a/compiler/optimizing/code_generator_arm64.h
+++ b/compiler/optimizing/code_generator_arm64.h
@@ -115,7 +115,7 @@
                           kParameterFPRegistersLength,
                           kArm64PointerSize) {}
 
-  Location GetReturnLocation(Primitive::Type return_type) {
+  Location GetReturnLocation(Primitive::Type return_type) const {
     return ARM64ReturnLocation(return_type);
   }
 
@@ -130,9 +130,10 @@
   virtual ~InvokeDexCallingConventionVisitorARM64() {}
 
   Location GetNextLocation(Primitive::Type type) OVERRIDE;
-  Location GetReturnLocation(Primitive::Type return_type) {
+  Location GetReturnLocation(Primitive::Type return_type) const OVERRIDE {
     return calling_convention.GetReturnLocation(return_type);
   }
+  Location GetMethodLocation() const OVERRIDE;
 
  private:
   InvokeDexCallingConvention calling_convention;