Handling non-C files when traversing dirs and system include dirs
Handling non-C files when traversing dirs and system include dirs

If non-C files are in the DB, they should be dependency files (headers
mostly). We need to check if they are up to date and reparse its
dependents if not.

Visit unexplored files that are in the systems include directory.

google/navc,google/navc,google/navc