Fixed building with a bazel with hdrs_check fixed again.

Change-Id: I015f66cd6e02e07efa367b96edd775015ac0abca
diff --git a/y2015/control_loops/drivetrain/BUILD b/y2015/control_loops/drivetrain/BUILD
index bdf7ba0..9dd71f0 100644
--- a/y2015/control_loops/drivetrain/BUILD
+++ b/y2015/control_loops/drivetrain/BUILD
@@ -54,6 +54,7 @@
     '//aos/common/controls:control_loop',
     '//y2015:constants',
     '//aos/common/controls:polytope',
+    '//aos/common:math',
     '//frc971/control_loops:state_feedback_loop',
     '//frc971/control_loops:coerce_goal',
     '//frc971/queues:gyro',