* init/job.h: Update prototype of job_change_goal.
(Job): Remove cause member.
* init/job.c (job_change_goal): Drop additional argument since cause
is no longer used.
(job_change_state, job_child_reaper, job_handle_event): Only pass
two arguments to job_change_goal.
* init/control.c (control_job_start, control_job_stop): Only pass
two argumenst to job_change_goal.
* init/tests/test_job.c (test_change_goal, test_change_state): Only
pass two arguments to job_change_goal.