Minor fixes to mips64 for the arch-specific optimisation framework.

Change-Id: I9d49ea61c732e4fc6b3393aa8778951e29ce4efe
diff --git a/compiler/optimizing/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index 953e733..9117e30 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -138,7 +138,7 @@
       : HGraphVisitor(graph), codegen_(codegen) {}
 
 #define DECLARE_VISIT_INSTRUCTION(name, super)     \
-  void Visit##name(H##name* instr);
+  void Visit##name(H##name* instr) OVERRIDE;
 
   FOR_EACH_CONCRETE_INSTRUCTION_COMMON(DECLARE_VISIT_INSTRUCTION)
   FOR_EACH_CONCRETE_INSTRUCTION_ARM(DECLARE_VISIT_INSTRUCTION)
@@ -168,7 +168,7 @@
   InstructionCodeGeneratorARM(HGraph* graph, CodeGeneratorARM* codegen);
 
 #define DECLARE_VISIT_INSTRUCTION(name, super)     \
-  void Visit##name(H##name* instr);
+  void Visit##name(H##name* instr) OVERRIDE;
 
   FOR_EACH_CONCRETE_INSTRUCTION_COMMON(DECLARE_VISIT_INSTRUCTION)
   FOR_EACH_CONCRETE_INSTRUCTION_ARM(DECLARE_VISIT_INSTRUCTION)