Make position.joint in claw.q use the right type.

Change-Id: I59405431f6bb97a027eba6eb6fb811b2d9bc6739
diff --git a/frc971/control_loops/claw/claw.q b/frc971/control_loops/claw/claw.q
index 51659be..8f5f9c0 100644
--- a/frc971/control_loops/claw/claw.q
+++ b/frc971/control_loops/claw/claw.q
@@ -22,7 +22,7 @@
   };
 
   message Position {
-    PotAndIndexPair joint;
+    PotAndIndexPosition joint;
   };
 
   message Output {