Fix sc-dev-plus-aosp builds am: 823f787a31 am: 07a72126b1

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/tools/aidl/+/16381824

Change-Id: I9a4dd27f8672343900a5b0c6b235a34096c76869
diff --git a/aidl_unittest.cpp b/aidl_unittest.cpp
index 7ea8c17..98744c2 100644
--- a/aidl_unittest.cpp
+++ b/aidl_unittest.cpp
@@ -32,6 +32,7 @@
 #include "aidl_language.h"
 #include "aidl_to_cpp.h"
 #include "aidl_to_java.h"
+#include "aidl_to_ndk.h"
 #include "comments.h"
 #include "logging.h"
 #include "options.h"