Use correct command-line option.

Test: TreeHugger.
Change-Id: I346949b66f48b04004de7e25422d7bd91d12a619
diff --git a/Android.bp b/Android.bp
index ef47958..366d02e 100644
--- a/Android.bp
+++ b/Android.bp
@@ -1,4 +1,4 @@
-// This file is generated by cargo2android.py --device --run --dependencies --test.
+// This file is generated by cargo2android.py --device --run --dependencies --tests.
 // Do not modify this file as changes will be overridden on upgrade.
 
 package {