Support importing generated configs

Change-Id: I260851684f809e05d0b486f62950cccc61cc53bc
diff --git a/aos/configuration.h b/aos/configuration.h
index a01a902..4ada459 100644
--- a/aos/configuration.h
+++ b/aos/configuration.h
@@ -20,7 +20,8 @@
 // Reads a json configuration.  This includes all imports and merges.  Note:
 // duplicate imports will result in a CHECK.
 FlatbufferDetachedBuffer<Configuration> ReadConfig(
-    const std::string_view path);
+    const std::string_view path,
+    const std::vector<std::string_view> &extra_import_paths = {});
 
 // Sorts and merges entries in a config.
 FlatbufferDetachedBuffer<Configuration> MergeConfiguration(