Function silc_schedule_task_del_by_context
SYNOPSIS
void silc_schedule_task_del_by_context(SilcSchedule schedule,
void *context);
DESCRIPTION
Deletes a task from the scheduler by the specified `context'.
It is safe to call this function in any place. Tasks may be removed
in task callbacks (including in the task's own task callback) and
in multi-threaded environment in other threads as well.