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/y2018/control_loops/superstructure/intake/intake.h b/y2018/control_loops/superstructure/intake/intake.h
index 09a7e4d..bec5ff6 100644
--- a/y2018/control_loops/superstructure/intake/intake.h
+++ b/y2018/control_loops/superstructure/intake/intake.h
@@ -5,6 +5,7 @@
 
 #include "aos/commonmath.h"
 #include "frc971/control_loops/control_loop.h"
+#include "frc971/zeroing/pot_and_absolute_encoder.h"
 #include "frc971/zeroing/wrap.h"
 #include "frc971/zeroing/zeroing.h"
 #include "y2018/constants.h"