Registered signal handlers for joysticks and control loops

This *should* prevent us from leeking messages.  I'm still seeing
leaks, so I bet we aren't fully set up to handle that yet.

Change-Id: Id4a8c5c1741db3e70a3d0a836667b957aba8165a
diff --git a/aos/input/joystick_input.h b/aos/input/joystick_input.h
index ec8b52a..b10b1ba 100644
--- a/aos/input/joystick_input.h
+++ b/aos/input/joystick_input.h
@@ -1,6 +1,8 @@
 #ifndef AOS_INPUT_JOYSTICK_INPUT_H_
 #define AOS_INPUT_JOYSTICK_INPUT_H_
 
+#include <atomic>
+
 #include "aos/common/input/driver_station_data.h"
 
 namespace aos {
@@ -18,6 +20,10 @@
  private:
   // Subclasses should do whatever they want with data here.
   virtual void RunIteration(const driver_station::Data &data) = 0;
+
+  static void Quit(int /*signum*/);
+
+  static ::std::atomic<bool> run_;
 };
 
 // Class which will proxy joystick information from UDP packets to the queues.