Add missing build dependency

Change-Id: Id557f1e704c1207bf067c8720c57eba20ab5f52f
diff --git a/debian/control b/debian/control
index 6b9299b..cdcd234 100644
--- a/debian/control
+++ b/debian/control
@@ -1,5 +1,6 @@
 Source: aiy-board-audio
 Maintainer: AIY Projects <support-aiyprojects@google.com>
+Build-Depends: debhelper
 
 Package: aiy-board-audio
 Section: sound