Move PDP measurement fetching to a separate thread

Stupid CAN messages are too slow for being inline with the normal
path...

Change-Id: I160a24eb3216fc54083df576555b5bcad062ceb8
diff --git a/frc971/wpilib/loop_output_handler.h b/frc971/wpilib/loop_output_handler.h
index d7b6283..972d7ef 100644
--- a/frc971/wpilib/loop_output_handler.h
+++ b/frc971/wpilib/loop_output_handler.h
@@ -1,12 +1,12 @@
 #ifndef FRC971_WPILIB_LOOP_OUTPUT_HANDLER_H_
 #define FRC971_WPILIB_LOOP_OUTPUT_HANDLER_H_
 
+#include <atomic>
+
 #include "aos/common/scoped_fd.h"
 #include "aos/common/time.h"
 #include "aos/common/util/log_interval.h"
 
-#include <atomic>
-
 namespace frc971 {
 namespace wpilib {