MIPS64: Implement virtual intrinsic slow path

This fixes a crash in dex2oat while compiling boot.oat.

Change-Id: I44fc92809902d7fc226c88b3e3f081b72cc19ce5
diff --git a/compiler/optimizing/code_generator_mips64.h b/compiler/optimizing/code_generator_mips64.h
index 9bbd027..4f91c71 100644
--- a/compiler/optimizing/code_generator_mips64.h
+++ b/compiler/optimizing/code_generator_mips64.h
@@ -333,10 +333,7 @@
       MethodReference target_method) OVERRIDE;
 
   void GenerateStaticOrDirectCall(HInvokeStaticOrDirect* invoke, Location temp) OVERRIDE;
-  void GenerateVirtualCall(HInvokeVirtual* invoke ATTRIBUTE_UNUSED,
-                           Location temp ATTRIBUTE_UNUSED) OVERRIDE {
-    UNIMPLEMENTED(FATAL);
-  }
+  void GenerateVirtualCall(HInvokeVirtual* invoke, Location temp) OVERRIDE;
 
   void MoveFromReturnRegister(Location trg ATTRIBUTE_UNUSED,
                               Primitive::Type type ATTRIBUTE_UNUSED) OVERRIDE {