Some controller signals only work on unix
control_signal_check() and control_signal_act hard-code the signal numbers to be the ones used in unix.
But handle_control_signal() uses the system-defined values for them.
One of these behaviors is wrong.
E.g., USR1 and USR2 (among possibly others) don't work on OS X from the controller.
[Automatically added by flyspray2trac: Operating System: All]