Support C++ and Rust interop with autocxx

Change-Id: Id2c852bf48ed58d6284e7ab8a388ac38419fc474
Signed-off-by: Brian Silverman <bsilver16384@gmail.com>
diff --git a/build_tests/hello_autocxx.h b/build_tests/hello_autocxx.h
new file mode 100644
index 0000000..8b6e285
--- /dev/null
+++ b/build_tests/hello_autocxx.h
@@ -0,0 +1,8 @@
+#ifndef BUILD_TESTS_HELLO_AUTOCXX_H_
+#define BUILD_TESTS_HELLO_AUTOCXX_H_
+
+#include <stdlib.h>
+
+int plain_function() { return 971; }
+
+#endif  // BUILD_TESTS_HELLO_AUTOCXX_H_