Ported the polydrivetrain code over to C++.
diff --git a/frc971/control_loops/drivetrain/drivetrain.gyp b/frc971/control_loops/drivetrain/drivetrain.gyp
index 8e98e4b..89a2321 100644
--- a/frc971/control_loops/drivetrain/drivetrain.gyp
+++ b/frc971/control_loops/drivetrain/drivetrain.gyp
@@ -23,15 +23,18 @@
       'sources': [
         'drivetrain.cc',
         'drivetrain_motor_plant.cc',
+        'polydrivetrain_motor_plant.cc',
       ],
       'dependencies': [
         'drivetrain_loop',
         '<(AOS)/common/common.gyp:controls',
         '<(DEPTH)/frc971/frc971.gyp:common',
+        '<(DEPTH)/aos/build/externals.gyp:libcdd',
         '<(DEPTH)/frc971/control_loops/control_loops.gyp:state_feedback_loop',
         '<(DEPTH)/frc971/queues/queues.gyp:queues',
       ],
       'export_dependent_settings': [
+        '<(DEPTH)/aos/build/externals.gyp:libcdd',
         '<(DEPTH)/frc971/control_loops/control_loops.gyp:state_feedback_loop',
         '<(AOS)/common/common.gyp:controls',
         'drivetrain_loop',