Building slycot from source.

Change-Id: I2e9df7a50749818bd4526161fbc50bca08e255e8
diff --git a/frc971/control_loops/python/BUILD b/frc971/control_loops/python/BUILD
index 747b49c..b79d676 100644
--- a/frc971/control_loops/python/BUILD
+++ b/frc971/control_loops/python/BUILD
@@ -8,4 +8,7 @@
     'polytope.py',
     'libcdd.py',
   ],
+  deps = [
+    '//external:slycot',
+  ],
 )