Each tool needs to be independent, which
meant that every time a tool was called,
it would build the entire system graph.
This was an obvious waste of time and resources.

Now, the tools build the graph based
on the requested services, which
drastically reduces the time needed to
construct the necessary dependency graph.

Do not warn the user about this feature. It only used on very specific case like module migration process.
Badly used, this features can easily broke the sanity of the system state

rename service_resolve_svtree function to service_intree. Rename struct ss_resolve_graph_style to info_graph_style

The check of the symlink can return true even if lstat return -1, so be sure to only pass if the lstat return 0 and the symlink check return true