Make all the serialization code build for the Teensy too

Change-Id: Ib3442220581553d78bb30e42818203959d987d85
diff --git a/y2019/jevois/structures.h b/y2019/jevois/structures.h
index fcc268e..28da405 100644
--- a/y2019/jevois/structures.h
+++ b/y2019/jevois/structures.h
@@ -11,6 +11,7 @@
 
 #include "aos/containers/sized_array.h"
 #include "aos/time/time.h"
+#include "third_party/GSL/include/gsl/gsl"
 
 namespace frc971 {
 namespace jevois {