* lang_clang/parsing/parse_clang.ml: better error message, include filename
* lang_clang/analyze/location_clang.ml: try sparse
* lang_clang/analyze/compile_commands_clang.ml: misc
* lang_clang/analyze/location_clang.ml: ctags
* lang_clang/analyze/graph_code_clang.ml: avoid dupe main(), treat it as
a static function