Split up zeroing library BUILD rules

There was no good reason for one build rule to have both the interface
and a bunch of implementations; split it up and make the relevant users
depend on the libraries directly.

Change-Id: If6a0aa49dd7ea588b7325604658bc0594db4aac0
Signed-off-by: James Kuszmaul <jabukuszmaul+collab@gmail.com>
diff --git a/frc971/control_loops/profiled_subsystem.h b/frc971/control_loops/profiled_subsystem.h
index dff5aad..1fa8ac2 100644
--- a/frc971/control_loops/profiled_subsystem.h
+++ b/frc971/control_loops/profiled_subsystem.h
@@ -15,6 +15,7 @@
 #include "frc971/control_loops/profiled_subsystem_generated.h"
 #include "frc971/control_loops/simple_capped_state_feedback_loop.h"
 #include "frc971/control_loops/state_feedback_loop.h"
+#include "frc971/zeroing/pot_and_index.h"
 #include "frc971/zeroing/zeroing.h"
 
 namespace frc971 {