actions and control loops: frc971 shall depend on aos

And not the other way around.

Define the loop frequency in actor.h and use that in
control_loop.h.  Fix dependencies (and add missing dependency of
actor on event_loop).

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: Ieec0b3eb1c66737e1ed19e6bdee40655524f4016
diff --git a/frc971/control_loops/control_loop.h b/frc971/control_loops/control_loop.h
index c02d094..3430dbd 100644
--- a/frc971/control_loops/control_loop.h
+++ b/frc971/control_loops/control_loop.h
@@ -4,6 +4,7 @@
 #include <atomic>
 #include <cstring>
 
+#include "aos/actions/actor.h"
 #include "aos/events/event_loop.h"
 #include "aos/time/time.h"
 #include "aos/util/log_interval.h"
@@ -15,7 +16,7 @@
 
 // Control loops run this often, "starting" at time 0.
 constexpr ::std::chrono::nanoseconds kLoopFrequency =
-    ::std::chrono::milliseconds(5);
+    aos::common::actions::kLoopFrequency;
 
 // Provides helper methods to assist in writing control loops.
 // It will then call the RunIteration method every cycle that it has enough