Attached patch adds support for proc.num key on HP-UX platform. I have tested it only on HP-UX 11.31, since I do not have any earlier version available, but according to documentation, the added code should work on earlier (supported) versions as well.

The patch is probably missing configure checks for certain used header files - I was not sure where exactly to add these checks (since they are platform-specific), so I would like some help with that.