7c4676ddee
new return codes of -1 were mistakenly being considered "true". Callout_stop now returns -1 to indicate the callout had either already completed or was not running and 0 to indicate it could not be stopped. Also update the manual page to make it more consistent no non-zero in the callout_stop or callout_reset descriptions. MFC after: 1 Month with associated callout change.