The error message should give all the hint needed. usleep is defined in unistd.h, is that file included in connection.cpp? If not add it.
- oop, nevermind.
Also check /etc/profile and /etc/rc.local
It's good that you read the wireless wiki page, but what have you *done* with that information? What errors have you received, and/or which step fails?
How about this:https://wiki.archlinux.org/index.php/Fan_Speed_Control
Can xsltproc run on a url or do you need to download the file(s) first?
The error message says to add libGL to the linker line. Did you do that?
Have you rebooted since your last kernel update?
Can you give examples of some of these programs so I can test it out?