Added the operator to frc971 SensorReader.

Took the operator fuction out of the year specific SensorReader, needed
to make a empty RunInteration in order for it to work.

Change-Id: I0ec02ab293c1f8eba56d6365383105e860f69cdd
diff --git a/frc971/wpilib/BUILD b/frc971/wpilib/BUILD
index 00cd77d..d0f6bce 100644
--- a/frc971/wpilib/BUILD
+++ b/frc971/wpilib/BUILD
@@ -289,6 +289,7 @@
     deps = [
         "//aos/stl_mutex",
         "//aos/time:time",
+        "//aos/util:phased_loop",
         "//aos:init",
         "//third_party:wpilib",
         ":dma",