Many of the functions we use implicitly are not part of the C standard
library so we have to specific that we're pulling from POSIX, X/Open,
BSD, or whatever standard we're using before we can rely on the
definition being available.
There's plenty of room for refactoring here since I mostly stopped at
just getting the functions being called to show up from their includes,
although I did replace rindex with strrchr since the latter is
standardized, and replaced uint with unsigned rather than trying to figure out
what header includes those.
(Updated to choose the right repository, this isn't libksysguard but instead kde/workspace/ksysguard)