Core/Jits: Adds an option to disable the register cache.

This will help to disable all inter-instruction dependencies.
So android users can check if only a single instruction is broken without compiling dolphin on their own.

Source/Core/DolphinQt/MenuBar.h

@@ -261,6 +261,7 @@ private:
   QAction* m_jit_paired_off;
   QAction* m_jit_systemregisters_off;
   QAction* m_jit_branch_off;
+  QAction* m_jit_register_cache_off;
 
   bool m_game_selected = false;
 };