This function was necessary for me because, after profiling my application, I found that the conventional sigar_proc_state_get wastes a lot of cycles in the proc_status_get function, which isn't necessary if you only want the ppid. I could've optimized it further (by directly getting the ppid instead of calling proc_state_read, which wastes a lot of cycles calling sigar_skip_token), but, the way it is, it's good enough for me.
This is for linux only (for now), but I think it's pretty easy to port to other platforms -- I'll have to port it to windows myself in the coming weeks.
Based in the sigar-1.6 branch.
